Solution Manual For Introduction to Computing and Programming in Python 4th Edition by Mercedes Gui

Solutions Manual for Introduction to Computing and Programming in Python: A Multimedia Approach, 4th Edition

By Mark J. Guzdial and Barbara Ericson

Solutions manual by Matthew Guzdial

© 2016 Pearson Education, Inc., Hoboken, NJ. All rights reserved.

Index Chapter 1- Page 1 Chapter 2- Page 7 Chapter 3- Page 14 Chapter 4- Page 21 Chapter 5- Page 29 Chapter 6- Page 40 Chapter 7- Page 64 Chapter 8- Page 70 Chapter 9- Page 83 Chapter 10- Page 101 Chapter 11- Page 145 Chapter 12- Page 157 Chapter 13- Page 168 Chapter 14- Page 185 Chapter 15- Page 200 Chapter 16- Page 206 Chapter 17- Page 213

Chapter 1 1.1 Every profession uses computers today. Use a Web browser and a search engine like Google to find sites that relate your field of study with computer science or computing or computation. For example, search for “biology computer science” or “management computing.”

A good answer should have at least 2-3 links. For example, for “biology” some good links would be: http://www.brown.edu/research/projects/computational-molecular-biology/ http://www.sciencedirect.com/science/article/pii/S0960982201000811 http://www.biomedcentral.com/1471-2105/12/120 1.2 The 2013 Nobel Prize in Chemistry was in some sense a Nobel Prize given for work in computer science. What was the role of computers in that Nobel Prize?

Computers were used to simulate the behavior of large molecules in a brand new way combining classical and quantum physics.

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(Source: http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2013/press.html) 1.3 Text characters are encoded in different ways. The bottom level is always binary in bytes, but a different binary pattern can be used to represent different characters. Two of these encodings are ASCII and Unicode. See if you can do Web searches on ASCII and Unicode. What’s the difference between ASCII and Unicode? Why would we need Unicode if we already had ASCII? The major difference between ASCII and Unicode is the amount of characters both hold.

ASCII has 128 characters, while Unicode has over 110,000 characters. Unicode is largely used for non-Latin letters, such as Chinese characters, (Sources: http://en.wikipedia.org/wiki/ASCII and http://en.wikipedia.org/wiki/Unicode) 1.4 Consider the representation for pictures described in Section 1.4, where each dot (pixel) in the picture is represented by three bytes, for the red, green, and blue components of the color at that dot. How many bytes does it take to represent a 640 by 480 picture, a common picture size on the Web? How many bytes does it take to represent a 1024 by 768 pictures, a common screen size? (What do you think is meant now by a “three megapixel” camera?)

Bytes for 640 by 480 picture: (640*480)*3 = 921,600 Bytes for a 1024 by 768: (1024*768)*3 = 2,359,296 A “three megapixel” camera means that the camera can capture images with three million pixels.

1.5 One bit can represent 0 or 1. With two bits you have four possible combinations 00, 01, 10, and 11. How many different combinations can you make with four bits or eight bits (one byte)? Each combination can be used to represent a binary number. How many numbers can you represent with 2 bytes (16 bits)? How many numbers can you represent with four bytes?

Four bits: 16 combinations (0000, 0001, 0010, 0100, 1000, 0011, 0110, 1100, 0101, 1010, 1001, 0111, 1110, 1101, 1011, 1111) Eight bits: 256 combinations Two bytes/16 bits: 65,536 combinations Four bytes/32 bits: 4,294,967,296 combinations 1.6 Microsoft Word used to use an encoding of a word-processing document called “DOC.” Most recent versions of Microsoft Word use a different encoding called “DOCX.” What’s the difference between them?

The “DOC” encoding was a unique encoding to Microsoft, while the “DOCX” encoding is based on XML, the Extendable Markup Language. This makes it easier for other programs to parse “DOCX” documents, along with conferring a number of other benefits

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(such as smaller size, higher quality images, and a lower chance of file corruption).

(Source: http://www.inc.com/software/articles/201002/doc.html and http://www.thebookdesigner.com/2013/04/docx-vs-doc/) 1.7 One of the powerful ideas in computer science is that encodings can be layered. Most of the encodings we’ve talked about so far (e.g., pixels in a picture, characters, floating point numbers) are based on binary. XML is a way of encoding information in text, which is in turn encoded in binary. What are the advantages and disadvantages of using XML rather than binary encodings?

Advantages: -XML is easy for humans and computers to read.

-XML is easily extendible -XML has been rapidly adopted by industry Disadvantages: -XML takes up more space than binary encoding -XML is extendible and therefore not as standardized (Source: http://www.mulberrytech.com/papers/HowAndWhyXML/slide009.html )

1.8 How can you encode a floating-point number in terms of bytes? Do a search on the Web for “floating point.” You will find that there are different encodings of floating point numbers. Take a common one like the IEEE Floating Point Standard as an example.

Assuming single precision, what is the largest and smallest numbers that you can represent in that encoding?

A computer can represent a floating-point number as it would an integer number, but with some extra information. Specifically, to be able to define the decimal portions of a floating point, a computer must know an extra integer to raise 10 by to multiply the base integer by. For example, if one was to represent the number 0.5 it would hold track of the number 5 and -1, since 0.5 equals 5 x10^(-1).

Smallest number: 1x10-101 Largest number: 9999999x1090 (Source: http://www.wikipedia.org/wiki/IEEE_floating_point) 1.9 As we said in the chapter, computer science is about people. Start your exploration of computer science by exploring the people who are computer scientists and influence computer science. As you do, find Web sites that you believe are credible for your information, and include the URL in your answers—with your reasons for believing that source is credible. What general rules do you use to determine what is a credible Web site?

Note: This question can be potentially confusing. Due to its structure, multiple

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interpretations are possible. There are essentially two sections, the first implicitly asking students to find people involved in computer science (and include the credible URL where they found them). The second part asks how to determine if a Web site is credible.

Some examples of people involved in computer science (and links): -Mark Guzdial (http://www.cc.gatech.edu/fac/mark.guzdial/) -Anita Borg (http://anitaborg.org/) -Bill Gates, Mark Zuckerberg, and Susan Wojcicki (http://www.mercurynews.com/business/ci_24308090/code-org-mark-zuckerberg-billgates-teach-computer-science-every-school ) Ways to determine if a link is credible: -If it ends with a “.edu” -If the link is a primary website for an organization or individual -If the link references other credible web sites 1.10 Look up Alan Kay, object-oriented programming, and the Dynabook on the Web. Alan is one of the inspirations for the media computation approach that we use in this book. Can you figure out what he has to do with media computation?

There are several potential answers to this question: -Alan Kay is considered one of the fathers of object oriented programming, which is used exclusively in this book (Source: http://amturing.acm.org/award_winners/kay_3972189.cfm) -Alan Kay is invested in educating all people in computer science (Source: http://www.vpri.org/) -Perhaps the best answer, Alan Kay is interested in making use of media-rich environments to teach computer science (Source: http://www.squeakland.org/) 1.11 Look up Clarence (Skip) Ellis. Without him, Google Docs wouldn’t work the way that they do to help people collaborate. What did he do?

Clarence Ellis is considered one of the pioneers of operational transformation, which deals with collaborative systems, such as those now used in Google Docs to allow for multi-user editing. (Source: https://cs.illinois.edu/news/memory-clarence-ellis-19432014) 1.12 Look up Grace Hopper on the Web. How did she contribute to programming languages?

Grace Hopper created the first compiler for a computer programming language and coined the term “debugging” for fixing computer flitches. (Source: http://en.wikipedia.org/wiki/Grace_Hopper#cite_note-Booss03-6) 1.13 Look up Andrea Lawrence on the Web. What computer science department did she chair?

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Andrea Lawrence chaired the computer and information sciences department of Spelman University (Source: http://www.thehistorymakers.com/biography/andrea-lawrence-42) 1.14 Look up Alan Turing on the Web. What does he have to do with our notion of what a computer can do and how encodings work?

Alan Turing created the definition for a modern computer in terms of what it can do, referred to as a “Turing Machine”. Additionally, he came up with a means of encoding an action table of a Turing machine as a string, such that someone can feed in instructions to a machine and get an output back. (Source: http://en.wikipedia.org/wiki/Universal_Turing_machine) 1.15 Look up Adele Goldberg on the Web. How did she contribute to programming languages?

She was a forerunner or pioneer in a number of now common facets of programming languages, including design patterns, object-oriented programming, and graphical user interfaces. (Source: http://en.wikipedia.org/wiki/Adele_Goldberg_%28computer_scientist%29) 1.16 Look up Kurt Gödel on the Web. What amazing things did he do with encodings?

He created Gödel numbering, a means by which a sequence of symbols can be represented as natural numbers (Source: http://en.wikipedia.org/wiki/G%C3%B6del_numbering) 1.17 Look up Ada Lovelace on the Web. What amazing things did she do before the first mechanical computer was built?

Ada Lovelace was the first ever computer programmer, before the first computer was even built, having come up with a stepwise sequence of operations for solving mathematical problems. (Source: http://www.computerhistory.org/babbage/adalovelace/) 1.18 Look up Claude Shannon on the Web. What did he do for his master’s thesis?

Claude Shannon proved in his master’s thesis that Boolean algebra could be used to simplify relays used in the electromechanical phone exchanges of the day, and later defined digital circuit design. (Source: http://dspace.mit.edu/bitstream/handle/1721.1/11173/34541425.pdf?sequence=1) 1.19 Look up Richard Tapia on the Web. What has he done to encourage diversity in computing?

Richard Tapia directed or co-directed more minority and women doctoral candidates in science and engineering than anyone in the country and has lead numerous programs to increase diversity in the fields of science and engineering. (Source: http://tapiaconference.org/about/tapia)

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1.20 Look up Marissa Mayer on the Web. What computer tool (that you probably use regularly) did she help create?

She helped to create Google’s now famous unadorned search page, along with the look and feel of some of the company’s most popular products. (Source: http://dealbook.nytimes.com/2012/07/16/googles-marissa-mayer-tapped-as-yahooschief/?hp) 1.21 Look up Shafi Goldwasser on the Web. What major computing prize did she win in 2012 and why?

The ACM Turing Award, which she won for work in the theoretic foundations for the science cryptography and pioneered new ways to check mathematical proofs. (Source: http://amturing.acm.org/award_winners/goldwasser_8627889.cfm) 1.22 Look up Mary Lou Jepsen on the Web. What new technology is she working on?

She is working on small screens that can seamlessly join together like legos to create larger screens, along with wall screens. (Source: http://www.fastcodesign.com/3036692/fast-feed/google-is-inventing-screens-that-snaptogether-like-lego) 1.23 Look up Ashley Qualls on the Web. What did she create that is worth a million dollars?

She created a website as a teenager that offered free MySpace account designs, making thousands of dollars from ad revenue alone. (Source: https://web.archive.org/web/20080220145135/http://potw.news.yahoo.com/s/potw/52250 /teen-millionaire) 1.24 Look up Tim Berners-Lee on the Web. What did he invent?

He implemented a communication protocol (Hypertext Transfer Protocol [HTTP]) that allowed for client and server communication via the Internet, thereby inventing the World Wide Web. (Source: http://www.w3.org/People/Berners-Lee/) 1.25 As in every field, people in computer science build on one another’s work. . Who invented the Logo Turtle?

Paul Wexelblat built the first turtle (Source: http://web.archive.org/web/20090310020335/http://www.erzwiss.unihamburg.de/Sonstiges/Logo/logofaqx.htm#FAQ2) . Who used the Logo Turtle to have fourth graders learn about fractions in mathematics?

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There are multiple answers to this question, including Idit Harel, or Yasmin B. Kafai.

(Source: http://investigations.terc.edu/library/bookpapers/research_on_logo.cfm) . Who invented a programming language that featured thousands of Logo Turtles in order to model complex behavior like ants and termites?

Uri Wilensky authored NetLogo, which allows for simulation and modeling of ant behavior and more. (Source: http://ccl.northwestern.edu/netlogo/index.shtml) 1.26 Now trace this series of who built on whose work. . Who invented the laser printer?

Gary Starkweather invented the laser printer. (Source: http://xenia.media.mit.edu/~yarin/laser/laser_printing.html) . One of the winners of the ACM Turing Award (the closest that computer science has to a Nobel Prize) invented a computer system for typesetting books on a laser printer. Who was that?

Donald Knuth built a system (referred to as TeX) to computationally typeset books for a laser printer.

(Source: http://amturing.acm.org/award_winners/knuth_1013846.cfm) . The winner of a recent ACM Turing Award built a computer system on top of the last typesetting system, to make it easier to use (but that’s not what he won the Turing Award for). Who was that, and what did he win his award for?

Leslie Lamport developed the LaTeX system written on top of TeX. He won his Turing Award in 2013 for contributions to distributed and concurrent systems, essentially when several computations are executed simultaneously, potentially interacting.

(Source: http://amturing.acm.org/award_winners/lamport_1205376.cfm)

Chapter 2 2.1 What is an algorithm?

Algorithm: A description of a process in a step-by-step manner, not tied to any programming language. The same algorithm may be implemented in many different languages in many different ways in many different programs—but they would all be the same process if we’re talking about the same algorithm. (Chapter 1, Page 9)

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What is an encoding?

Encoding: The means by which computers convert information into a particular form, for example, from bytes to numbers to text. Note, the book does not contain an explicit definition of encoding, but the two important things to get across are 1) the encoding’s use in translating between different types of information and 2) tat the computer makes use of multiple layers of encoding. (Chapter 1, Page 10) What is the difference between an algorithm and a program?

A program is just one possible implementation of an algorithm within one computer language. The same algorithm can be expressed in many different languages in many different ways in many different programs. (Chapter 1, Page 9) 2.2 How can computers represent pictures as numbers?

Each image is composed of tiny dots called pixels, each composed of a sum of red, green, and blue. The red, green, and blue values of a pixel are each represented as a byte; bytes can then be represented as a number. (Pixel Information: Chapter 1, Pages 11-12; Byte Information: Chapter 1, Pages 9-10) How can computers represent text as numbers?

Computers can represent text via ASCII (American Standard Code for Information Interchange) encoding. Using this encoding, the number 65 is interpreted as the capital letter A, 66 is interpreted as the capital letter B, and so on. Each individual character of a piece of text can then become a collection of numbers. (Chapter 1, Page 10) Remember that the computer can only represent integer numbers in raw binary. How can computers represent floating-point (decimal) numbers?

A computer can represent a floating-point number as it would an integer number, but with some extra information. Specifically, to be able to define the decimal portions of a floating point, a computer must know an extra integer to raise 10 by to multiply the base integer by. For example, if one was to represent the number 0.5 it would hold track of the number 5 and -1, since 0.5 equals 5 x10^(-1). Note: This is not explained in the book, but Chapter 1, Question 1.8 suggests looking up IEEE floating point encoding that represents floating-points in this way. wikipedia.org/wiki/IEEE_floating_point has a good write-up of this approach.

2.3 What does def mean? What does the statement def someFunction(x,y): do?

The keyword “def” is used by Python to define new functions. The statement defines a function with the title “someFunction” and the inputs “x” and “y”. The code directly after this function header will be executed when the function is called. (Chapter 2, Page 34)

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2.4 What does print mean? What does the statement print a do?

The keyword “print” means “Display a readable representation of whatever follows.”

(Chapter 2, Page 23) The statement “print a” will do different things depending if “a” is a defined variable or not. If it is, Python will print the value of that variable in a readable form. So if a = 5, the number 5 will be printed to the console. If the variable “a” is not defined, Python will print: A local or global name could not be found. You need to define the function or variable before you try to use it in any way.

(Chapter 2, Pages 24-25) 2.5 What is the output from print 1 / 3? Why do you get this output?

0. You get this output as both 1 and 3 are assumed to be integer numbers by Python.

Since integer numbers only allow for whole numbers, the answer to “How many times does 3 go into 1” is “0”.

2.6 What is the output from print 1.0 / 3? Why do you get this output?

0.3333333333333333. You get this output as Python recognized 1.0 as a floating point number, meaning that it allows for a decimal number answer, the same you would get on a calculator.

2.7 What is the output from print 10 + 3 * 7? Why do you get this output?

31. You get this output as Python follows the order of operations, such that multiplication (3*7=21) occurs before addition (10+21).

2.8 What is the output from print (10 + 3) * 7? Why do you get this output?

91. You get this output as Python follows the order of operations, such that calculations within parenthesis occur before multiplication.

2.9 What is the output from print "Hi" + "there"? Why do you get this output?

Hithere. You get this output as Python implements addition between str types (strings) by concatenating the second str on to the first.

2.10 What is the output from print "Hi" + 10? Why do you get this output?

The error value is: cannot concatenate 'str' and 'int' objects Inappropriate argument type.

An attempt was made to call a function with a parameter of an invalid type. This means that you did something such as trying to pass a string to a method that is expecting an integer.

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You get this output as Python does not have a standard way to add or concatenate an int (integer) onto a str (string).

2.11 What is the output from print "Hi" * 10? Why do you get this output?

HiHiHiHiHiHiHiHiHiHi You get this output as Python recognizes multiplying a str (string) by an int (integer) as a desire to repeat that str the number of times represented by the int.

2.12 What is the output from print "Hi" + "there"? Why do you get this output?

Note: This is a repeat of 2.9 2.13 What is the output from print "Hi" * "10"? Why do you get this output?

The error value is: can't multiply sequence by non-int of type 'str' Inappropriate argument type.

An attempt was made to call a function with a parameter of an invalid type. This means that you did something such as trying to pass a string to a method that is expecting an integer.

You get this output as Python has no standard way to multiply two str types (strings) together.

2.14 What is the output from print "Hi" + "10"? Why do you get this output?

Hi10 You get this output as, while “10” may seem to be a number the symbol “ on both sides indicate that is a str type variable (string). As such, python simply concatenates it to the end of “Hi”.

2.15 What does show(p) do? (Hint: There’s more than one answer to this question.)

If p is defined as a variable, then Python will print to the console the value of p. If p has no value, Python will print out: A local or global name could not be found. You need to define the function or variable before you try to use it in any way.

(Chapter 2, Pages 24-25) 2.16 What is the output from the following? >>> a = 3 >>> b = 4 >>> x = a * b >>> print x

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12 2.17 What is the output from the following? >>> a = 3 >>> b = -5 >>> x = a * b >>> print x -15 2.18 What is the output from the following? >>> a = 3 >>> b = -5 >>> a = b >>> b = 22 >>> x = a * b >>> print x -110 2.19 What is the output from the following? >>> a = 4 >>> b = 2 >>> x = a / b >>> print x 2 2.20 What is the output from the following? >>> a = 4 >>> b = 2 >>> x = b - a >>> print x -2 2.21 What is the output from the following? >>> a = -4 >>> b = 2 >>> c = abs(a) >>> x = a * c >>> print x -16 2.22 What is the output from the following? >>> name = "Barb" >>> name = "Mark"

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>>> print name Mark 2.23 What is the output from the following? >>> first = "Abe" >>> last = "Lincoln" >>> print first + last AbeLincoln (Note: No space should exist in the outputted string) 2.24 What is the output from the following? >>> first = "Abe" >>> last = "Lincoln" >>> print first + “ “ +last Abe Lincoln Abe Lincoln (Note: There should be a space between Abe and Lincoln) 2.25 What is the output from the following? >>> first = "Abe" >>> last = "Lincoln" >>> swap = first >>> first = last >>> last = swap >>> print first + " " + last Lincoln Abe 2.26 What is the output from the following? >>> a = ord("A") >>> b = 2 >>> x = a * b >>> print x 130. Note: The function ord returns the integer value of a character using ASCII encoding. In this case that value is 65.

2.27 What is being computed by the following?

The program is computing the time in seconds, minutes, and weeks that it would take a turtle to travel from Miami to Seattle at the “turtleSpeed” rate. In this case, 0.5 m/s 2.28 What is being computed from the following?

The program is computing the escape velocity required to leave the earth’s gravity.

Changing the gravity, earthMass, or earthRadius values could allow you to calculate the

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value for another planet.

2.29 What is being computed from the following?

The amount of time it would take to fall to the ground from the top of a building with heightInStories stories and with each story feetPerStory tall.

2.30 The following code gives the error message shown below. Fix the code.

The issue is that the call to the method “pickAFile()” is case-sensitive, such that the call to “pickafile()” will not be registered as the same thing. Therefore, the A and F should be capitalized.

(Chapter 2, Page 26) Note: There may be some confusion as to what the question refers to. A student could potentially misunderstand and believe there is no code to be fixed or that they should define a new method called “pickafile”. However, if the student read the chapter, it should be obvious what to do.

2.31 The following code gives the error message shown below. Fix the code.

The problem is that the variable “d” is not defined. Therefore, all that has to be done is to define d to something such that it can be multiplied by 3 (the value of “a”). It could then be either any sort of number or even a string. For example: >>> a = 3 >>> b = 4 >>> d = 4 >>> c = d * a >>> c 12 OR >>> a = 3 >>> b = 4 >>> d = “HI” >>> c = d * a >>> c ‘HIHIHI’ 2.32 What happens if you multiply a number by a string, like 3 * "Hello"?

‘HelloHelloHello’ is outputted What happens if you try to multiply a string by a string, "a" * "b"?

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You get the error message: The error value is: can't multiply sequence by non-int of type 'str' Inappropriate argument type.

An attempt was made to call a function with a parameter of an invalid type. This means that you did something such as trying to pass a string to a method that is expecting an integer.

2.33 But what is the name pickAFile anyway?

The name pickAFile is used to tell Jython to run the code within the pickAFile method.

Note: It points Jython to that section of code, and this type of variable is thus sometimes called a “function pointer”.

What do you get if you print pickAFile? <function pickAFile at 0x21> How about print makePicture? <function makePicture at 0x22> What prints, and what do you think it means?

Note: This section of this question is intentionally open-ended and a student should not be expected to know at this point. What it actually means is the section of memory where the function pointer is defined.

2.34 Try running the code below. What is the result?

5 Why did you get that? (Hint: “becomes the name for the value of.”)

The console prints out 5 as the variable myFunc is now the same value as the variable abs. In this case, myFunc is now equivalent to the absolute value function, which returns the absolute value of -5.

Chapter 3 3.1 You are running a bingo game where you want to tweet the winner of each round of the game. You want to announce the name of who won, and how much they won in dollars. Make a function that takes those two words in as input, and then announces the

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win. For now, just print the statement that you will want to tweet later. (Hint: Remember that you are taking a number as input, which has to be converted to a string to concatenate it.) def bingo(name, amount): amountStr = str(amount) print name + “ called Bingo! winning $”+amountStr Note: Information on the function “str” in Chapter 3, Page 46. Students may choose different variable names.

3.2 You are a race official on an ultra marathon (100 miles), and you want to display the number and elapsed time for each runner on a big display. Write a program to generate the phrase for the display based on the runner number, the mile marker, and the elapsed time. def runner(runnerNumber, marker, elapsedTime): runnerStr = str(runnerNumber) markerStr = str(marker) print “Runner #”+runnerStr+” passed mile “+markerStr+” at time “+elpasedTime 3.3 The pyramid function in this chapter doesn’t quite line up with “=” character as input.

Try some others, like “n” and “m” and “t”. The last one seems to line up best. Why? The character “t” lines up best as it’s the closest in width to the space character. All the other characters look lopsided because they are much wider, meaning they extend far more to the right than they should to make the pyramid even.

3.4 Create a function like the pyramid function that does the upside-down version. Your function invertedPyramid should also take an input character and print an inverted pyramid. def invertedPyramid(char): space = " " print 9*char print space ,7*char print 2*space ,5*char print 3*space ,3*char print 4*space,char 3.5 Using for loops and using the same techniques as the pyramid function, create a textsquare function that takes in two values as input: the character to use in making the square, and the size of the square in characters. Then print out a square of that many characters. def textsquare(char, size):

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space = " " for index in range(size): line = char+space*(size-2)+char if index==0: line= char*size if index==size-1: line= char*size print line Note: This is a tricky question, with many potential solutions. The important thing to watch out for is that the printed square is just outlined in the passed in character, as it is in the example. Code that prints out a solid square of that character is not acceptable.

3.6 We fixed justvowels so that it works with lowercase or uppercase vowels. Fix notvowels so that it doesn’t print out uppercase vowels. (Try it as it is in the chapter, and you will see that it does print uppercase vowels, even though the function is supposed to only print not vowels.) Actually, do two versions of notvowels, using each of the two methods that we used to fix justvowels.

1. Explicitly checking for uppercase vowels: def notvowels(string): for letter in string: if not (letter in "aeiouAEIOU"): print letter 2. Using the string method “lower()”: def notvowels(string): for letter in string: if not letter.lower() in "aeiou": print letter Note: This version does not explicitly check for consonants, but just if a character is not a vowel. One could instead remove the “not” and check against “qwrtypsdfghjklzxcvbnmQWRTYPSDFGHJKLZXCVBNM” and “qwrtypsdfghjklzxcvbnm” or some variation thereof.

3.7 One of the below programs that when called like this (with the underscore representing a digit from 1 to 4) generates this output: >>> dup_("rubber duck") ’kcud rebburrubber duck’ “dup3” generates the desired output. “dup1” just returns the passed in value. “dup2” returns the passed in string repeated a number of times equal to the size of the passed in

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string, beginning with a “_” character. “dup4” returns a reversed version of a passed in string.

3.8 Try giving our doubledutch program a full name like “John Smith.” What happens to the space?

The space is treated as a consonant, such that you get a response like: JuJohuhnun u SuSmumituthuh What if you include punctuation like periods or hyphens?

Anything that is not a vowel is treated as a consonant, therefore periods and hyphens are also treated as consonants. Therefore you get responses like: >>> doubledutch("Mr. John Brown-Smith") MuMrur.u. u JuJohuhnun u BuBrurowuwnun-u-SuSmumituthuh How could you create more full featured doubledutch that gets around these problems?

There are a couple of ways to get around these problems. One way is to simply check first if there are any special characters in the string. Otherwise, one could explicitly list all consonants, instead of simply checking if characters are not vowels.

3.9 Write a program that accepts a string as input, then prints out the vowels in that string and then prints the consonants in that string.

This is simply a matter of combining justvowels and notvowels: def splitem(name): vowels= "" consonants = "" for letter in name: if letter.lower() in "aeiou": vowels = vowels + letter if letter.lower() in "qwrtypsdfghjklzxcvbnm": consonants = consonants + letter print "Vowels: "+vowels print "Consonsants: "+consonants Note: This version explicitly checks for consonants, instead if a character is not a vowel.

A version in which that line is replaced with: if not letter.lower() in "aeiou": would also be acceptable.

3.10 Change the encode function so that spaces are simply skipped. def encode(string,keyletters): alpha="abcdefghijklmnopqrstuvwxyz" secret = "" for letter in string:

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if not letter.lower() in " ": index = alpha.find(letter) secret = secret+keyletters[index] print secret 3.11 Change the encode function so that punctuation is simply skipped. def encode(string,keyletters): alpha="abcdefghijklmnopqrstuvwxyz" secret = "" for letter in string: if not letter.lower() in ",.?:;-_'!": index = alpha.find(letter) secret = secret+keyletters[index] print secret Note: This code does not skip spaces, but one could add a space to the check against string to accomplish that.

3.12 The buildCipher function could create more complicated alphabets. As long as both the receiver and the sender generate the alphabet in the same way, the message needs to only include the keyword for encoding and decoding to work. Try building these variations: Put the keyword at the end of the alphabet, rather than the front: Note: This is accomplished simply by changing the final line. def buildCipher(key): alpha="abcdefghijklmnopqrstuvwxyz" rest = "" for letter in alpha: if not( letter in key ): rest = rest + letter print rest+key Reverse the alphabet before concatenating it to the keyword: Note: This is accomplished by adding a reversal of the “rest” variable prior to concatenating. def buildCipher(key): alpha="abcdefghijklmnopqrstuvwxyz" rest = "" for letter in alpha: if not( letter in key ): rest = rest + letter

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restReverse = "" for letter in rest: restReverse = letter+restReverse print key + restReverse Separate the vowels and the consonants in the rest of the alphabet so that the cipher alphabet is keyword, then the rest of the vowels, then the rest of the consonants: Note: We can simply duplicate the work from 3.9 to achieve the desired effect. def buildCipher(key): alpha="abcdefghijklmnopqrstuvwxyz" rest = "" for letter in alpha: if not( letter in key ): rest = rest + letter vowels= "" consonants = "" for letter in rest: if letter.lower() in "aeiou": vowels = vowels + letter if letter.lower() in "qwrtypsdfghjklzxcvbnm": consonants = consonants + letter print key + vowels + consonants 3.13 One of the below programs that when called like this (with the underscore representing a digit from 1 to 4) generates this output: >>> dup_("alphabet") ’_alphabetalphabetalphabetalphabetalphabetalphabetalphabetalphabet’ “dup2” is the correct program from below question 3.7 as it begins the returned string with an underscore and repeats the passed in string a number of times equal to the string’s length.

Note: Students may be confused by the wording “below programs”, as none of the dupTimes programs output the correct value. dupTimes1 returns 'aallpphhaabbeett', dupTimes2 returns 'lpphhhaaaabbbbbeeeeeettttttt', dupTimes3 returns '_alphabet', and dupTimes4 does not compile.

3.14 One of the below programs that when called like this (with the underscore representing a digit from 1 to 4) generates this output:

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>>> findem_ (4) ’abcdabcdabcdabcdabcdabcda’ “findem4” returns the desired output, once the “\” symbol has been removed.

Note: The last three functions all have “\” symbols before the “%” symbol that causes them not to compile. “findem4” returns the output due to the modulo operation leading to asking for the same indexes several times over. This can be seen by stepping through the for loop. On the 0th step, the function adds the 0th index of the letters string to the variable piles. This continues with each step adding that index till the 4th step, where the modulo operation again leads to the 0th index, then for the 5th step the 1st index and so on.

3.15 One of the below programs that when called like this (with the underscore representing a digit from 1 to 4) generates this output: >>> mixem_("we hold these truths") ’w.e. .h.o.l.d. .t.h.ese truths’ “mixem2” returns the desired output.

Note: “mixem2” simply adds periods after each character for the first half of the string, then adds the second half of the passed in string.

3.16 You have written an essay for school, and it has to be at least five pages long. But your essay is only 4.5 pages long! You decide to use your new Python skills to make your essay longer by spacing out the letters. Write a function that takes a string and a number of spaces to insert between each letter, then print out the resulting string. def spaceitout(astring, number): pile = "" space = " " for index in range(0,len(astring)-1): pile = pile+ astring[index]+number*space pile+=astring[len(astring)-1] print pile Note: The question specifically calls for spaces to be inserted between each letter.

Therefore, a solution such as: def spaceitout(astring, number): pile = "" space = " " for index in range(0,len(astring)): pile = pile+ astring[index]+number*space print pile

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Would be close, but actually have extra spaces after the final character as well.

3.17 Same problem as before, but you decide to use more of your new Python skills. You are going to increase the spaces between the words. Write a function that takes a string and a number of spaces to insert between each word, then print out the resulting string. def spaceout(astring, number): pile = "" space = " " parts = astring.split() for index in range(0,len(parts)-1): pile = pile+ parts[index]+number*space pile = pile+parts[len(parts)-1] print pile Note: Information on the “split()” method can be found on Chapter 3, Page 63.

Additionally, the question specifically calls for spaces to be inserted between each word, not after each, which requires an implementation similar to the above. A simpler function that prints spaces after every word, even the last one, would be: def spaceout(astring, number): pile = "" space = " " parts = astring.split() for index in range(0,len(parts)): pile = pile+ parts[index]+number*space print pile

Chapter 4 4.1 Why don’t we see red, green, and blue spots at each position in our picture?

Because each pixel is made up of a combination of red, green, and blue, not three distinct spots of each. (Note: Chapter 4, Page 77) What is hierarchical decomposition? What is it good for?

Hierarchical decomposition is a problem solving technique of breaking a complex problem into simpler and simpler parts until you can solve each part. It’s good for creating complex programs out of pieces that you understand. (Note: Chapter 4, Page 99)

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What is luminance?

There are couple potential answers to this question based on the book: -The human visual system for processing black and white (Source: Chapter 4, Page 76) -The intensity of a color, that can be computed with the formula (red+green+blue)/3 (Source: Chapter 4, Page 104) Why is the maximum value of any color component (red, green, or blue) 255?

Because eight bits can represent 256 unique combinations we have a maximum value of 255, since one combination must account for 0. (Source: Chapter 4, Page 78) The color encoding we’re using is RGB. What does this mean, in terms of the amount of memory required to represent color? Is there a limit to the number of colors that we can represent? Are there enough colors representable in RGB? RGB means that every color is made up of a combination of three different primary colors, each represented by eight bits each. This gives us a total of twenty-four bits of color possibilities, for a total of 16,777,216 colors. Humans can see more than sixteen million colors, but since no device exists that can express all the color variations we can see, the RBG model is enough.

(Source: Chapter 4, Page 78) 4.2 Program 34 (page 89) obviously reduces the red by too much. Write a version that only reduces the red by 10%, then one by 20%. Can you find pictures where each is most useful? Note that you can always repeatedly reduce the red in a picture but you don’t want to have to do it too many times.

10% version: def decreaseRed(picture): for pix in getPixels(picture): value=getRed(pix) setRed(pix,value*0.1) 20% version: def decreaseRed(picture): for pix in getPixels(picture): value=getRed(pix) setRed(pix,value*0.2) 4.3 Write the blue and green versions of the reduce red function—Program 9 (page 56).

Note: The program it refers to is actually the reduce red function, Program 34 (page 89). def decreaseBlue(picture):

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for pix in getPixels(picture): value=getBlue(pix) setBlue(pix,value*0.5) def decreaseGreen(picture): for pix in getPixels(picture): value=getGreen(pix) setGreen(pix,value*0.5) 4.4 Each of the following is equivalent to the increase red function—Program 35 (page 94). Test them and convince yourself that they work. Which do you prefer and why?

Note: This is an open-ended question as there are reasons to prefer both. increaseRed2: This program is much slimmer, taking up only three lines. It also avoids creating unnecessary variables. increaseRed3: This program takes up much more space than “increaseRed2”, but its much clearer exactly what’s happening.

4.5 If you keep increasing the red value and wrapping is on, eventually some pixels become bright green and blue. If you check those pixels with the picture tool, you’ll find that the values of red are very low. What do you think is going on? How did they get so small? How does wrapping work?

What’s going on is that because a color can only be of values 0-255, so if wrapping is turned on, any value above 255 just wraps to the modulo remainder. So if you’re upping the red values by 10 each time, and you are already at 255, you’ll end up with 255+10=260%255 = 10. In that way you can go from a very large value to a very small one while increasing.

(Source: Chapter 4, Page 94) 4.6 Write a function to swap the values of two colors, for example, swap the red value with the blue value. def swapRedBlue(picture): for pix in getPixels(picture): valueBlue=getBlue(pix) valueRed=getRed(pix) setRed(pix,valueBlue) setBlue(pix,valueRed) Note: You could pick any swap combination of the three colors (red, green, or blue). The only change would be in which “get” and which “set” methods were used.

OR def swapRedBlue(picture): for pix in getPixels(picture):

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valueBlue=getBlue(pix) valueRed=getRed(pix) valueGreen=getGreen(pix) setColor(pix,makeColor(valueBlue,valueGreen,valueRed)) 4.7 Write a function to set the red, green, and blue values to zero. What is the result? def setAllZero(picture): for pix in getPixels(picture): setRed(pix,0) setBlue(pix,0) setGreen(pix,0) OR def setAllZero(picture): for pix in getPixels(picture): setColor(pix, makeColor(0,0,0)) The result is the entire image is set to black.

4.8 Write a function to set the red, green, and blue values to 255. What is the result? def setAllMax(picture): for pix in getPixels(picture): setRed(pix,255) setBlue(pix, 255) setGreen(pix, 255) OR def setAllMax(picture): for pix in getPixels(picture): setColor(pix, makeColor(255, 255, 255)) The result is the entire image is set to white.

4.9 What does the following function do? “test1” sets all the red values in the passed in picture to a third of their current value.

4.10 What does the following function do? “test2” increases all of the blue values in the passed in picture by fifty percent.

4.11 What does the following function do? “test3” sets all of the green values in the picture to zero.

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4.12 What does the following function do? “test4” increases all the values of the pixels of the picture by ten.

4.13 What does the following function do? “test5” decreases all of the values of the pixels of the picture by twenty.

4.14 What does the following function do? “test6” swaps the values of the colors for each pixel in the game. It sets the blue values to the red values, the red values to the green values, and the green values to the blue values.

4.15 What does the following function do? “test7” halves all the color values for each pixel of the picture.

4.16 What does the following function do? By reading the program without running it, do you think that the result of test8 will be lighter or darker than the result of test7? “test8” sets all color values in the picture to a third of their current value, it will therefore lead to a darker image than “test7” that only halves the values.

4.17 What does the following function do? By reading the program without running it, do you think that the result of test9 will be lighter or darker than the result of test7? “test9” doubles the current color values for each pixel of the picture, it will therefor lead to a lighter image than “test7” that halves the values.

4.18 Write a function to “blue-ify” a face. Write a function that accepts a picture as input.

If any pixel has a blue value less than 150, then set that pixel’s color to white. Try it on a picture of a face and see what you get. def blueify(picture): for pix in getPixels(picture): value = getBlue(pix) if value<150: setColor(pix,white) Note: If the picture is dark enough, checking for values less than 150 may lead to a mostly white image.

4.19 Write a general “blue-ify” function. Write a function that accepts a picture as input, then doubles the blue value of every pixel and cut the red and green values in half. def blueify2(picture): for pix in getPixels(picture): valueB = getBlue(pix)*2

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valueR = getRed(pix)/2 valueG = getGreen(pix)/2 setColor(pix,makeColor(valueR,valueG,valueB)) 4.20 Write a general “red-ify” function. Write a function that accepts a picture as input, then doubles the red value of every pixel and cut the blue and green values in half. def redify(picture): for pix in getPixels(picture): valueB = getBlue(pix)/2 valueR = getRed(pix)*2 valueG = getGreen(pix)/2 setColor(pix,makeColor(valueR,valueG,valueB)) 4.21 Write a function to change a picture to grayscale and then negate it.

Note: All one has to do is combine the grayscale and negate methods (Program 42 and Program 41 respectively). def grayscale(picture): for p in getPixels(picture): intensity = (getRed(p)+getGreen(p)+getBlue(p))/3 setColor(p,makeColor(intensity ,intensity ,intensity)) for px in getPixels(picture): red=getRed(px) green=getGreen(px) blue=getBlue(px) negColor=makeColor(255-red, 255-green, 255-blue) setColor(px,negColor) OR (more simply) def grayscale(picture): for p in getPixels(picture): intensity = (getRed(p)+getGreen(p)+getBlue(p))/3 intensity = 255-intensity setColor(p,makeColor(intensity ,intensity ,intensity)) 4.22 Write a function to create a lightened grayscale image. First, lighten the image by adding 75 to the red, green, and blue components of every pixel. Since higher numbers are closer to white, this should make the pixel lighter. Now, grayscale the new image. def grayscale2(picture): for p in getPixels(picture): valueR = getRed(p)+75 valueG = getGreen(p)+75 valueB = getBlue(p)+75

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setColor(p,makeColor(valueR ,valueG ,valueB)) for p in getPixels(picture): intensity = (getRed(p)+getGreen(p)+getBlue(p))/3 setColor(p,makeColor(intensity ,intensity ,intensity)) OR (more simply) def grayscale2(picture): for p in getPixels(picture): valueR = getRed(p)+75 valueG = getGreen(p)+75 valueB = getBlue(p)+75 intensity = (valueR+valueG+valueB)/3 setColor(p,makeColor(intensity ,intensity ,intensity)) 4.23 Write a function to create a lightened grayscale image, by use makeLighter. First, lighten the image by using the makeLighter function on each color. Now, grayscale the new image. Compare the result to the picture created by the previous problem. How does makeLighter compare to adding 75 to each of the red, green, and blue components of every pixel? def grayscale3(picture): for p in getPixels(picture): color = getColor(p) color = makeLighter(color) setColor(p,color) intensity = (getRed(p)+getGreen(p)+getBlue(p))/3 setColor(p,makeColor(intensity ,intensity ,intensity)) Adding 75 to each red, green, and blue component outputs a much brighter image than using makeLighter, except when using an already very bright image with wrapping turned off.

(Source: Chapter 4, Page 109) 4.24 Write three functions, one to clear blue (Program 36 (page 94)) and one to clear red, and one to clear green. For each of these, which would be the most useful in actual practice? How about combinations of them?

Note: You don’t need to write a clearBlue function, just copy the one on page 94. def clearBlue(picture): for p in getPixels(picture): setBlue(p,0) def clearRed(picture): for p in getPixels(picture): setRed(p,0)

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def clearGreen(picture): for p in getPixels(picture): setGreen(p,0) While all of them could potentially be useful as a means of making an image look different for artistic purposes, clearing out the red (assuming little to no red elsewhere in the image) could help to avoid red-eye problems with flash photography. A combination could also work for artistic purposes, seeing as it would leave you with an image that had only values of the same primary color.

Note: There may be multiple potential answers to the second part of this question.

4.25 Rewrite the clear blue program (Program 36 (page 94)) to maximize blue (i.e., set it to 255) instead of clearing it. Is this useful? Would the red or green versions of the maximize function be useful? Under what conditions? def maximizeBlue(picture): for p in getPixels(picture): setBlue(p,255) This could potentially be useful for artistic reasons, for example to make an image appear to be taken under water. Red or green versions could also be useful for artistic purposes.

4.26 Write a function that takes a picture as input, and make the top half of the picture black. def setHalfBlank(picture): pixels = getPixels(picture) for index in range(0,len(pixels)/2): pixel = pixels[index] setColor(pixel ,black) 4.27 The function copyHalf copied the top half of the picture into the bottom half. Write a new function copyUpHalf that copies the bottom half of the picture into the top. def copyUpHalf(picture): pixels = getPixels(picture) for index in range(0,len(pixels)/2): pixel1 = pixels[index + len(pixels)/2] color1 = getColor(pixel1) pixel2 = pixels[index] setColor(pixel2 ,color1) 4.28 The function mirrorHalf mirrors the top half of the picture onto the bottom half.

Write a new function mirrorUpHalf that mirrors the top half of the picture into the top.

Note: The question should read “mirrors the bottom half of the picture into the top”

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def mirrorHalf(picture): pixels = getPixels(picture) target = len(pixels) – 1 for index in range(0,len(pixels)/2): pixel1 = pixels[target] color1 = getColor(pixel1) pixel2 = pixels[index] setColor(pixel2 ,color1) target = target - 1

Chapter 5 5.1 Write a function called changeColor that takes as input a picture and an amount to increase or decrease a color by and a number 1 (for red), 2 (for green), or 3 (for blue).

The amount will be a number between −.99 and .99. def changeColor(picture, amount, number): for p in getPixels(picture): if number==1: value = getRed(p) value = value +value*amount setRed(p,value) if number ==2: value = getGreen(p) value = value +value*amount setGreen(p,value) if number ==3: value = getBlue(p) value = value +value*amount setBlue(p,value) Note: Because of the requirements of the question, unlike in the previous chapter the value variable can’t just be multiplied by the amount variable. If one did it that way, they’d end up with a image with ninety percent of the red removed with the function all “changeColor(pict,−.10,1)” and not the ten percent requested.

5.2 Imagine that you have a picture, and you are painting a copy of it. But you have only eight colors. Write a function that inputs a picture, and makes these changes to each pixel. For each of red, green, and blue, if the component is less than 100, make it zero.

Otherwise, make it 255. def paintLimited(picture): for p in getPixels(picture): valueR = getRed(p) if valueR<100: setRed(p,0)

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else: setRed(p,255) valueG = getGreen(p) if valueG<100: setGreen(p,0) else: setGreen(p,255) valueB = getBlue(p) if valueB<100: setBlue(p, 0) else: setBlue(p,255) 5.3 Write a function that inputs a picture, a color, and a number. The number is the width of a border that you are to draw on all four sides of the picture, with the given color. You can assume that the number will always be an integer less than 50. def makeBorder(picture, border, number): width = getWidth(picture) height = getHeight(picture) for p in getPixels(picture): x = getX(p) y = getY(p) if x<number: setColor(p, border) elif x>(width-number-1): setColor(p, border) if y<number: setColor(p, border) elif y>(height-number-1): setColor(p, border) Note: To achieve the desired effect one has to use “height-number-1” or “width-number1” instead of “height-1” and “width-1” or the border will not be the correct size.

5.4 The process we used to draw borders could actually be used to draw lines as well. For example, if you have a square picture, every pixel whose x value equals its y value lies on the diagonal from upper-left to lower-right corners. Write a function that inputs a square picture (you can assume square) and an input color, and draws a diagonal line from upper-left to lower-right using the input color for the line color. def drawDiagonal(picture, lineColor): for p in getPixels(picture): x = getX(p)

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y = getY(p) if x==y: setColor(p,lineColor) 5.5 Write a function that uses the same process to draw a vertical line down the middle of the picture, and a horizontal line across the middle of the picture, neatly separating the picture into four quadrants. This function can work for any square or rectangular picture. def drawQuadrants(picture, lineColor): vertical = getWidth(picture)/2 horizontal = getHeight(picture)/2 for p in getPixels(picture): x = getX(p) y = getY(p) if y==vertical: setColor(p,lineColor) if x==horizontal: setColor(p,lineColor) Note: The question does not specify that a line color should be passed in, so one can just write a function that always uses the same color.

5.6 It’s a little more tricky to write a function that draws a diagonal from lower-left to upper-right for a square picture. Note that the sum of the x and the y should be equal to the number of pixels in the line. def drawDiagonal2(picture, lineColor): width = getWidth(picture) for p in getPixels(picture): x = width-getX(p) y = getY(p) if x==y: setColor(p,lineColor) Note: The question does not specify that a line color should be passed in, so one can just write a function that always uses the same color.

5.7 Write a function to put 10 pixel wide “prison cell bars” on the left border, center, and right border of an input picture. def prisonbars(picture, lineColor): width = getWidth(picture) center = width/2 for p in getPixels(picture):

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x = width-getX(p) if x<10: setColor(p,lineColor) elif x>width-11: setColor(p,lineColor) if (x>center-5) and (x<center+6): setColor(p,lineColor) Note: The question does not specify that a line color should be passed in, so one can just write a function that always uses the same color.

Additionally the middle bar is difficult to get at exactly ten pixels across and centered.

The above is one way to ensure that the bar is ten pixels across, but it will only be centered in certain images with uneven widths. Another solution that is not stringent concerning the ten pixels across but will always be centered is: def prisonbars(picture, lineColor): width = getWidth(picture) center = width/2 for p in getPixels(picture): x = width-getX(p) if x<10: setColor(p,lineColor) elif x>width-11: setColor(p,lineColor) difference = abs(center-x) difference = abs(difference) if difference<6: setColor(p,lineColor) 5.8 Write a function that posterizes an input picture along a very specific process. If the red value is greater than 180, then set the pixel to red. If not, then check if the blue value is greater than 180, and if so, set the pixel to blue. If not, then check if the green value is greater than 180, and if so, set the pixel to green. If none of the three channels is greater than 180, set the pixel to black. def posterize(picture): for p in getPixels(picture): if getRed(p)>180: setColor(p,red) elif getBlue(p)>180:

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setColor(p,blue) elif getGreen(p)>180: setColor(p,green) else: setColor(p,black) 5.9 Write a function that pinkifies white in a picture. Input a picture, then check each pixel to see if the red, green, and blue are all over 100. If so, set that pixel to pink. def pinkify(picture): for p in getPixels(picture): if (getRed(p)>100) and (getGreen(p)>100) and (getBlue(p)>100): setColor(p,pink) 5.10 Write a function that decreases red by 50% on the left side of the picture, and increases it by 200% on the right side. def alterReds(picture): center = getWidth(picture)/2 for p in getPixels(picture): x= getX(p) if x<center: redVal = getRed(p)*0.5 setRed(p,redVal) elif x>center: redVal = getRed(p)*2 setRed(p,redVal) 5.11 Write a function to make lighter the left side of a picture, and turn the right side into a grayscale. def halfsies(picture): center = getWidth(picture)/2 for p in getPixels(picture): x= getX(p) if x<center: c = getColor(p) setColor(p,makeLighter(c)) elif x>center: intensity = (getRed(p)+getGreen(p)+getBlue(p))/3 setColor(p,makeColor(intensity,intensity,intensity)) Note: Use of the function makeLighter is not required for the left size of the image, but is implied in the wording. One could also have increased the value of each pixel with new code.

5.12 Write a function that treats horizontal thirds of the picture differently. Make the top

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third of an input picture brighter, then the middle third decrease blue and green by 30%, then the bottom third should be made negative. def thirdsies(picture): firstThird = (getHeight(picture)/3.0) secondThird = (getHeight(picture)/3.0)*2 for p in getPixels(picture): y= getY(p) if y<firstThird: c = getColor(p) setColor(p,makeLighter(c)) elif (y>firstThird) and (y<secondThird): blueVal = getBlue(p)-getBlue(p)*0.3 greenVal = getGreen(p)-getGreen(p)*0.3 setBlue(p,blueVal) setGreen(p,greenVal) elif y>secondThird: redVal = 255-getRed(p) greenVal = 255-getGreen(p) blueVal = 255-getBlue(p) setColor(p,makeColor(redVal,greenVal,blueVal)) Note: Use of the function makeLighter is not required for the left size of the image. One could also have increased the value of each pixel with new code.

5.13 Rewrite Program 52 (page 124) using this helper function to make it much shorter. def posturize(picture): for p in getPixels(picture): setRed(p,pickPosterizeValue(getRed(p))) setGreen(p,pickPosterizeValue(getGreen(p))) setBlue(p,pickPosterizeValue(getBlue(p))) 5.14 What will be printed for this function if you executed each of these: (a) testMe (1, 2, 3) Hello 9 3 (b) testMe (3, 2, 1) Hello Hello Hello 7

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1 (c) testMe (5, 75, 20) 20 Hello Hello Hello Hello Hello 5 20 5.15 Start with a picture of someone you know and make some specific color changes to it: • Turn the teeth purple.

• Turn the eyes red.

• Turn the hair orange.

Of course, if your friend’s teeth are already purple, or eyes red, or hair orange, choose a different target color. def monsterify(picture, teethStartX, teethStartY, teethEndX, teethEndY, teethColor, teethDistance, eyesStartX, eyesStartY, eyesEndX, eyesEndY, eyesColor, eyesDistance, hairStartX, hairStartY, hairEndX, hairEndY, hairColor, hairDistance): for px in getPixels(pic): x = getX(px) y = getY(px) if (teethStartX <= x <= teethEndX) and (teethStartY <= y <= teethEndY): if (distance(teethColor,getColor(px)) < teethDistance): setColor(px,makeColor(255,0,255)) if (eyesStartX <= x <= eyesEndX) and (eyesStartY <= y <= eyesEndY): if (distance(eyesColor,getColor(px)) < eyesDistance): setColor(px,red) if (hairStartX <= x <= hairEndX) and (hairStartY <= y <= hairEndY): if (distance(hairColor,getColor(px)) < hairDistance): setColor(px,orange) Note: The solution above will work for any image, but could easily have been tailored to a specific one given the way the question was stated.

5.16 Write a program checkLuminance that will input red, green, and blue values, and compute the luminance using the weighted average (as below). But then print out a warning to the user based on the computed luminance: • If the luminance is less than10, “That’s going to be awfully dark.”

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• If the luminance is between 50 and 200, “Looks like a good range.”

• Over 250, “That’s going to be nearly white!” def checkLuminance(redValue, greenValue, blueValue): luminance = (redValue+greenValue+blueValue)/3 if luminance <10: print "That's going to be awfully dark." if (luminance >50) and (luminance<200): print "Looks like a good range." if luminance>250: print "That's going to be nearly white!"

5.17 Try doing chromakey in a range. The picture “statue-tower.jpg” has a blue, but not blue enough background to work with chromakeyBlue. However, if youchangetheruletogetRed(px) + getGreen(px) < getBlue(px)+100, it works great for the sky—but messes up near the ground.

Change chromakeyBlue to use the modified rule, and apply it to “statue- tower.jpg.” def chromakeyBlue(source ,bg): for px in getPixels(source): x = getX(px) y = getY(px) if (getRed(px) + getGreen(px) < getBlue(px)+100): bgpx = getPixel(bg,x,y) bgcol = getColor(bgpx) setColor(px,bgcol) Now, write chromakeyBlueAbove to take in an input picture, a new background, and a number. The number is a y value, and you should only do chromakey to pixels above that input y. Apply it to “statue-tower.jpg” so that the blue of the sky gets changed to the moon or the jungle, but the area near the ground is not touched.

Note: Though the question says “pixels above that input y” it should read “pixels below that input y” in order for the sky to be affected but not the ground since y values get larger as you move down the picture. def chromakeyBlueAbove(source ,bg, number): for px in getPixels(source): x = getX(px) y = getY(px) if y<number: if (getRed(px) + getGreen(px) < getBlue(px)+100): bgpx = getPixel(bg,x,y) bgcol = getColor(bgpx) setColor(px,bgcol) Note: The second part of the question does not state whether to use the old or modified

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rule, but using the old one would not have the proper effect on the sky.

5.18 Try doing background subtraction in a range. Take the “dog-bg.jpg” and “nodogbg.jpg” pictures as input, with an upper left-hand corner x and y, and lower right-hand corner x and y. Do background subtraction just around the dog in the chair, leaving the leaves and the house alone. def swapBack(pict,bg,newBg, startX, startY, endX, endY): for px in getPixels(pict): x = getX(px) y = getY(px) if (x>startX) and (x<endX): if(y>startY) and (y<startY): bgPx = getPixel(bg,x,y) pxcol = getColor(px) bgcol = getColor(bgPx) if (distance(pxcol,bgcol)<15.0): newcol=getColor(getPixel(newBg ,x,y)) setColor(px,newcol) 5.19 Write a function to blend two pictures, starting with the top third of the first picture and then blend the two together in the middle third and then show the last third of the second picture. This works best if the two pictures are the same size.

Note: Assuming the same size in this response is acceptable def blendTwoPictures(pict,secondPict): firstThird = getHeight(pict)/3.0 secondThird = (2*getHeight(pict)/3.0) for px in getPixels(pict): x = getX(px) y = getY(px) if (y>firstThird) and (y<secondThird): redValOne = getRed(px)/2 greenValOne = getGreen(px)/2 blueValOne = getBlue(px)/2 secondPx = getPixel(secondPict,x,y) redValTwo = getRed(secondPx)/2 greenValTwo = getGreen(secondPx)/2 blueValTwo = getBlue(secondPx)/2 setColor(px, makeColor(redValOne+redValTwo, greenValOne+greenValTwo, blueValOne+blueValTwo)) elif (y>secondThird-1):

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secondPx = getPixel(secondPict,x,y) pxcol = getColor(secondPx) setColor(px,pxcol) Note: Since we just make changes to the first picture there’s no reason to do anything for the first third.

5.20 Write a function to interleave two pictures taken as input. Take the first 20 pixels from the first picture and then 20 pixels from the second picture and then the next 20 pixels from the first picture and then the next 20 pixels from the second picture and so on till all the pixels have been used. def interleavePictures(pic, picTwo): numPixels = 0 for px in getPixels(pic): numPixels = numPixels +1 x = getX(px) y = getY(px) val = numPixels/20 if val%2 ==1: secondPx = getPixel(picTwo, x, y) pxcol = getColor(secondPx) setColor(px,pxcol) Note: There are many different ways to accomplish the interleaving. The important thing is that the switch occurs every 20 pixels, not how it occurs. One possibility is to track which of the two pictures the function pulls from at any moment, such as: def interleavePictures(pic, picTwo): numPixels = 0 currentPicture = 1 for px in getPixels(pic): numPixels = numPixels +1 x = getX(px) y = getY(px) if numPixels ==20: if currentPicture==1: currentPicture = 2 elif currentPicture==2: currentPicture = 1 numPixels = 0 if currentPicture==2: secondPx = getPixel(picTwo, x, y)

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pxcol = getColor(secondPx) setColor(px,pxcol) 5.21 Write a function to blend two pictures: 25% of one picture blended with 75% of another. def blendpics(pic, picTwo): for px in getPixels(pic): x = getX(px) y = getY(px) redValOne = getRed(px)*0.25 greenValOne = getGreen(px)*0.25 blueValOne = getBlue(px)*0.25 secondPx = getPixel(picTwo, x, y) redValTwo = getRed(secondPx)*0.75 greenValTwo = getGreen(secondPx)*0.75 blueValTwo = getBlue(secondPx)*0.75 setColor(px, makeColor(redValOne+redValTwo, greenValOne+greenValTwo, blueValOne+blueValTwo)) 5.22 Rewrite Program 52 (page 124) to use an if with an else. def posterize(picture): #loop through the pixels for p in getPixels(picture): #get the RGB values red = getRed(p) green = getGreen(p) blue = getBlue(p) red = getRed(p) green = getGreen(p) blue = getBlue(p) #check and set red values if(red < 64): if(red > 63 and red < 128): setRed(p, 95) elif(red > 127 and red < 192): setRed(p, 159) elif(red > 191 and red < 256): setRed(p, 223) else: setRed(p, 31) #check and set green values if(green < 64): if(green > 63 and green < 128): setGreen(p, 95) elif(green > 127 and green < 192): setGreen(p, 159)

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elif(green > 191 and green < 256): setGreen(p, 223) else: setGreen(p, 31) #check and set blue values if(blue < 64): if(blue > 63 and blue < 128): setBlue(p, 95) elif(blue > 127 and blue < 192): setBlue(p, 159) elif(blue > 191 and blue < 256): setBlue(p, 223) else: setBlue(p, 31) Note: To meet the requirements of the question, the function also has to include “elif” along with “if” and “else” parts.

5.23 Why do moviemakers use a green or blue screen for special effects instead of a red screen?

Moviemakers use blue or green as there’s less overlap with common colors like those found on many faces.

(Source: Chapter 4, Page 133) 5.24 Get some green posterboard and take a picture of a friend in front of it. Now use chromakey to put her or him in the jungle. Or better yet, in Paris.

An inclusion of the image is all that’s required for this question, the function is already on pages 134-135: def chromakeyGreen(source ,bg): for px in getPixels(source): x = getX(px) y = getY(px) if (getRed(px) + getBlue(px) < getGreen(px)): bgpx = getPixel(bg,x,y) bgcol = getColor(bgpx) setColor(px,bgcol)

Chapter 6 6.1 Write a function to pull out just Jenny’s eyes, rather than remove the red in them, and paste them into a canvas. def copyEyes (): # Set up the source and target pictures

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src = makePicture("jenny-red.jpg") canvas = makeEmptyPicture (getWidth(src) ,getHeight(src)) # Now , do the actual copying for sourceX in range(0,getWidth(src)): for sourceY in range(0,getHeight(src)): if (sourceX>108) and (sourceX<(108+91)) and (sourceY>201) and (sourceY<(201+107)): color = getColor(getPixel(src,sourceX,sourceY)) setColor(getPixel(canvas ,sourceX ,sourceY), color) show(src) show(canvas) return canvas Note: The values for the area around the eyes are found from Chapter 5, Page 120, but any values that include the eyes will do. Additionally, any canvas size and eye pasting location will do, these were just the easiest.

6.2 Rewrite the Jenny’s eyes function to double Jenny’s eyes, making them appear twice. def copyEyes2 (): # Set up the source and target pictures src = makePicture("jenny-red.jpg") canvas = makeEmptyPicture (getWidth(src) ,getHeight(src)) # Now , do the actual copying for sourceX in range(0,getWidth(src)): for sourceY in range(0,getHeight(src)): if (sourceX>108) and (sourceX<(108+91)) and (sourceY>201) and (sourceY<(201+107)): color = getColor(getPixel(src,sourceX,sourceY)) setColor(getPixel(canvas ,sourceX ,sourceY), color) setColor(getPixel(canvas, sourceX, sourceY+214), color) show(src) show(canvas) return canvas 6.3 The black in the function copyHorseFaceSmallBlack doesn’t look great on that horse.

Would red look better? Try it.

def copyHorseFaceSmallRed (): hcol = makeColor (216 ,169 ,143) # Set up the source and target pictures src = makePicture("horse.jpg") canvas = makeEmptyPicture (163 ,308) # Now , do the actual copying targetX = 0

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for sourceX in range(104,267): targetY = 0 for sourceY in range (114 ,422): color = getColor(getPixel(src,sourceX,sourceY)) if distance(color ,hcol) < 40: setColor(getPixel(canvas ,targetX ,targetY), red) else: setColor(getPixel(canvas ,targetX ,targetY), color) targetY = targetY + 1 targetX = targetX + 1 show(canvas) return canvas 6.4 Create a movie poster by drawing text on a picture.

Note: The student merely has to make use of the addText(pict,x,y,string) function described on Chapter 6, Page 188.

6.5 Create a comic strip by putting three to four pictures next to each other horizontally and adding text.

Note: This could be done with several methods, but one can also use a single method like the below to put together the image. The point of the question is simply to make a comic strip with JES though. The function will work for three pictures in a row all of the same height. def makeAComic(picture1, picture2, picture3, text1, x1, y1, text2, x2, y2, text3, x3, y3): width1 = getWidth(picture1) width2 = getWidth(picture2) width3 = getWidth(picture3) height = getHeight(picture1) canvas = makeEmptyPicture ((width1+width2+width3) ,height) targetX = 0 for sourceX in range(0,width1): targetY = 0 for sourceY in range (0 ,height): color = getColor(getPixel(picture1,sourceX,sourceY)) setColor(getPixel(canvas ,targetX ,targetY), color) targetY = targetY + 1 targetX = targetX + 1 targetX = 0 for sourceX in range(width1,(width1+width2)): targetY = 0 for sourceY in range (0 ,height):

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color = getColor(getPixel(picture2,sourceX,sourceY)) setColor(getPixel(canvas ,targetX ,targetY), color) targetY = targetY + 1 targetX = targetX + 1 targetX = 0 for sourceX in range((width1+width2),(width1+width3+width3)): targetY = 0 for sourceY in range (0 ,height): color = getColor(getPixel(picture3,sourceX,sourceY)) setColor(getPixel(canvas ,targetX ,targetY), color) targetY = targetY + 1 targetX = targetX + 1 addText(canvas, x1, y1, text1) addText(canvas, x2, y2, text2) addText(canvas, x3, y3, text3) 6.6 Using the drawing functions, draw a bull’s eye.

Note: While not mentioned in this chapter, the easiest way to accomplish this task is with the “addOval” and “addOvalFilled” methods available in JES. These can be found in JES Functions > Pictures. Using them you can get a method like: def makeBullseye(): canvas = makeEmptyPicture(100,100) addOval(canvas, 10,10, 80,80) addOval(canvas, 20,20, 60,60) addOval(canvas, 30,30, 40,40) addOvalFilled(canvas,40,40,20,20,black) return canvas

Note: The other way to accomplish this task is by using the addLine function, but doing so means much less nice rings for one’s bull’s eye, unless a student goes pixel by pixel.

For example: def makeBullseye(): canvas = makeEmptyPicture(100,100) addLine(canvas, 20,10,10,20)

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addLine(canvas, 10,20,10,35) addLine(canvas, 10,35,20,45) addLine(canvas, 20,45,35,45) addLine(canvas, 35,45,45,35) addLine(canvas, 45,35,45,20) addLine(canvas, 45,20,35,10) addLine(canvas, 20,10,35,10) addLine(canvas, 22,25,25,22) addLine(canvas, 25,22,29,22) addLine(canvas, 29,22,32,25) addLine(canvas, 32,25,32,29) addLine(canvas, 22,25,22,29) addLine(canvas, 22,29,25,32) addLine(canvas, 25,32,29,32) addLine(canvas, 29,32,32,29) return canvas

6.7 Using the drawing tools presented here, draw a house—just go for the simple child’s house with one door, two windows, walls, and a roof. def makeHouse(): canvas = makeEmptyPicture(100,100) #walls and door addRect(canvas, 20, 40, 60, 59) addRect(canvas, 45, 80, 10, 19) #roof addLine(canvas,0,40,50,0) addLine(canvas,50,0,100,40) addLine(canvas,0,40,100,40) #windows addRect(canvas, 25, 60, 9, 19) addLine(canvas,25,70,34,70) addLine(canvas,30,60,30,79) addRect(canvas, 65, 60, 9, 19)

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addLine(canvas,65,70,74,70) addLine(canvas,70,60,70,79) return canvas

6.8 Draw horizontal and vertical lines on a picture with 10 pixels between the lines.

Note: This is simple enough to do as it simply means taking Program 87 and changing both 5’s to 10’s. Like so: def lineExample (): img = makePicture(pickAFile()) verticalLines(img) horizontalLines(img) show(img) return img def horizontalLines(src): for x in range(0,getHeight(src),10): for y in range(0,getWidth(src)): setColor(getPixel(src,y,x),black) def verticalLines(src): for x in range(0,getWidth(src),10): for y in range(0,getHeight(src)): setColor(getPixel(src,x,y),black) 6.9 Draw horizontal and vertical lines on a picture where the gap between the lines increases linearly. Start at 10, then 12, then 14.

Note: The important part here is to make sure the value you add on by is increasing by two every time. def lineExample2 (): img = makePicture(pickAFile()) verticalLines(img) horizontalLines(img) show(img)

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return img def horizontalLines(src): increase = 0 multi = 0 for x in range(0,getHeight(src),2): for y in range(0,getWidth(src)): if x==increase: setColor(getPixel(src,y,(x)),black) if x==increase: increase = increase+10+multi*2 multi = multi+1 def verticalLines(src): increase = 0 multi = 0 for x in range(0,getWidth(src)): for y in range(0,getHeight(src)): if x==increase: setColor(getPixel(src,(x),y),black) if x==increase: increase = increase+10+multi*2 multi = multi+1 6.10 Draw diagonal lines on a picture from top left to bottom right using addLine.

Note: This question can potentially be confusing as it suggests that multiple lines need to be drawn, but does not give precise instructions. To simplify, one can assume that they should draw two lines to get from the top left to bottom right, as below: def lineDiagonal (): img = makePicture(pickAFile()) midHeight = getHeight(img)/2 midWidth = getWidth(img)/2 addLine(img, 0, 0, midWidth, midHeight) addLine(img, midWidth, midHeight, getWidth(img), getHeight(img)) show(img) return img 6.11 Draw diagonal lines on a picture from top right to bottom left using addLine.

Note: See above question for justification. def lineDiagonal2 ():

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img = makePicture(pickAFile()) midHeight = getHeight(img)/2 midWidth = getWidth(img)/2 addLine(img, getWidth(img), 0, midWidth, midHeight) addLine(img, midWidth, midHeight, 0, getHeight(img)) show(img) return img 6.12 What is a vector-based image? How does it differ from a bitmapped image? When is it better to use a vector-based image?

A vector-based image is an image in which the picture is stored not as pixels, but as instructions, like a program. It is better to use vector-based images if the image is simple, or if you want to be able to change the image consistently (for example: scaling an image to different sizes).

(Source: Chapter 6, Pages 189-191) 6.13 Draw a house on the beach where we put the mysterious box previously.

Note: The answer to this question can be achieved by combining the answer to 6.8 and Program 88. def addAHouse (): beach = makePicture("beach.jpg") makeHouse(beach, 190,320) show(beach) return beach

def makeHouse(canvas, x, y): #walls and door addRect(canvas, 20+x, 40+y, 60, 59) addRect(canvas, 45+x, 80+y, 10, 19) #roof addLine(canvas,0+x,40+y,50+x,0+y) addLine(canvas,50+x,0+y,100+x,40+y) addLine(canvas,0+x,40+y,100+x,40+y) #windows addRect(canvas, 25+x, 60+y, 9, 19) addLine(canvas,25+x,70+y,34+x,70+y) addLine(canvas,30+x,60+y,30+x,79+y)

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addRect(canvas, 65+x,60+y, 9, 19) addLine(canvas,65+x,70+y,74+x,70+y) addLine(canvas,70+x,60+y,70+x,79+y) 6.14 Now use your house function to draw a town with dozens of houses at different sizes. You’ll probably want to modify your house function to draw at an input coordinate, then change the coordinate where each house is drawn. def createATown (): canvas = makeEmptyPicture(600, 400) makeHouse(canvas, 140,50, 1,1) makeHouse(canvas, 10,120, 2,2) makeHouse(canvas, 300,80, 3,3) makeHouse(canvas, 223,70, 1,1) show(canvas) return canvas def makeHouse(canvas, x, y, xMult, yMult): #walls and door addRect(canvas, 20*xMult+x, 40*yMult+y, 60*xMult, 59*yMult) addRect(canvas, 45*xMult+x, 80*yMult+y, 10*xMult, 19*yMult) #roof addLine(canvas,0+x,40*yMult+y,50*xMult+x,0+y) addLine(canvas,50*xMult+x,0+y,100*xMult+x,40*yMult+y) addLine(canvas,0+x,40*yMult+y,100*xMult+x,40*yMult+y) #windows addRect(canvas, 25*xMult+x, 60*yMult+y, 9*xMult, 19*yMult) addLine(canvas,25*xMult+x,70*yMult+y,34*xMult+x,70*yMult+y) addLine(canvas,30*xMult+x,60*yMult+y,30*xMult+x,79*yMult+y) addRect(canvas, 65*xMult+x,60*yMult+y, 9*xMult, 19*yMult) addLine(canvas,65*xMult+x,70*yMult+y,74*xMult+x,70*yMult+y) addLine(canvas,70*xMult+x,60*yMult+y,70*xMult+x,79*yMult+y)

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6.15 Write a function to draw a simple face with eyes and a mouth on a picture Note: There’s no need to make use of ovals to solve this problem, one can simply make use of rectangles and lines. def drawPicture(): canvas = makeEmptyPicture(100,100) makeFace(canvas, 0, 0) show(canvas) return canvas; def makeFace(canvas, x, y): addOval(canvas, x+10, y+60, 80, 30) addRectFilled(canvas, x+10, y+60, 80, 10, white) addOval(canvas, x+20, y+20, 10, 10) addOval(canvas, x+70, y+20, 10, 10)

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6.16 Now use your simple face function in a loop to draw a whole crowd of people. def drawCrowd(): canvas = makeEmptyPicture(500,100) for x in range(0, getWidth(canvas),100): makeFace(canvas, x, 0) show(canvas) return canvas; def makeFace(canvas, x, y): addOval(canvas, x+10, y+60, 80, 30) addRectFilled(canvas, x+10, y+60, 80, 10, white) addOval(canvas, x+20, y+20, 10, 10) addOval(canvas, x+70, y+20, 10, 10)

6.17 Draw a rainbow—use what you know about colors, pixels, and drawing operations to draw a rainbow. Is this easier to do with our drawing functions or by manipulating individual pixels? Why? Note: Without knowing about the addOvalFilled function by checking through the JES helper functions, this problem is much more difficult, as below: def drawRainbow(): canvas = makeEmptyPicture(21,20) makeArc(canvas,7, 7, red) makeArc(canvas,7, 8, orange) makeArc(canvas,7, 9, yellow) makeArc(canvas,7, 10, green)

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makeArc(canvas,7, 11, blue) makeArc(canvas,7, 12, makeColor(255,0,255)) show(canvas) return canvas; def makeArc(src, x, y, color): setColor(getPixel(src,(x),y),color) setColor(getPixel(src,(x+1),y-1),color) setColor(getPixel(src,(x+2),y-2),color) setColor(getPixel(src,(x+3),y-2),color) setColor(getPixel(src,(x+4),y-2),color) setColor(getPixel(src,(x+5),y-1),color) setColor(getPixel(src,(x+6),y),color)

The only helper function available according to the book that allows one to set the color is the “addRectFilled” function, which would not make a particularly good rainbow as it does not arc correctly. Therefore, its easier to make a small rainbow by setting individual colors.

Note: If one does know about the “addOvalFilled” JES helper function, one could solve the problem like so: def drawRainbow(): canvas = makeEmptyPicture(100,100) addOvalFilled(canvas, 0, 50, 100, 100, red) addOvalFilled(canvas, 5, 55, 90, 100, orange) addOvalFilled(canvas, 10, 60, 80, 100, yellow) addOvalFilled(canvas, 15, 65, 70, 100, green) addOvalFilled(canvas, 20, 70, 60, 100, blue) addOvalFilled(canvas, 25, 75, 50, 100, makeColor(255,0, 255)) addOvalFilled(canvas, 30, 80, 40, 100,white) show(canvas) return canvas

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It is much easier to make a rainbow with the addOvalFilled function as it allows one to easily capture the arc of a rainbow, as opposed to having to set each pixel by hand.

6.18 Which of the programs below takes a picture and removes all the blue from every pixel that already has a blue value of more than 100?

The answer is number two: D only.

What do the other ones do?

A. Sets the blue value of the top left 100 by 100 pixels of a picture to 100.

B. For each pixel in the picture, if it has any blue value, sets the blue value to 100.

C. For each pixel in the picture, if the distance from its color to the color (0, 0, 100) is greater than 100, set its blue value to 0.

6.19 def newFunction(a, b, c): print a list1 = range(0,4) value = 0 for x in list1: print b value = value +1 print c print value If you call the function above by typing: newFunction("I", "you", "walrus"), what will print?

I you you you you walrus 4 6.20 We’ve seen that if you increment the source picture index by 2 while incrementing the target picture index by 1 for each copied pixel, you end up with the source being scaled down onto the target. What happens if you increment the target picture index by 2 as well? What happens if you increment both by 0.5 and use int to get just the integer part?

If one increments the target picture index by 2 as well then one ends up copying over every other pixel. def copyEveryOtherPixel ():

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# Set up the source and target pictures src=makePicture(pickAFile()) canvas = makeEmptyPicture(getWidth(src),getWidth(src)) sourceX = 0 for targetX in range(0, (getWidth(src)),2): sourceY = 0 for targetY in range(0, (getHeight(src)),2): color = getColor(getPixel(src,sourceX,sourceY)) setColor(getPixel(canvas ,targetX ,targetY), color) sourceY = sourceY + 2 sourceX = sourceX + 2 show(canvas) return canvas If one increments both by 0.5, then you end up stretching out the image, while also skipping over every other pixel. def stretchAndCopyEveryOther (): # Set up the source and target pictures src=makePicture(pickAFile()) canvas = makeEmptyPicture(getWidth(src)*2,getWidth(src)*2) sourceX = 0.0 for targetX in range(0,(getWidth(src)*2),2): sourceY = 0.0 for targetY in range(0,(getHeight(src)*2),2): color = getColor(getPixel(src,int(sourceX),int(sourceY))) setColor(getPixel(canvas ,int(targetX) ,int(targetY)), color) sourceY = sourceY + 0.5 sourceX = sourceX + 0.5 show(canvas) return canvas 6.21 Write a function to mirror along the diagonal from (0, 0) to (width, height). def mirrorDiagonal(source): for y in range(0,getHeight(source)): for x in range(y,getWidth(source)): topPixel = getPixel(source ,x,y) bottomPixel = getPixel(source,y,x) color = getColor(topPixel) setColor(bottomPixel ,color) show(source) Note: This function only works particularly well with square images.

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6.22 Write a function to mirror along the diagonal from (0, height) to (width, 0). def mirrorDiagonal2(source): h = getHeight(source) w = getWidth(source) for y in range(0,h): for x in range(0,w-1-y , 1): topPixel = getPixel(source,x,y) bottomPixel = getPixel(source,h-1-y,w-1-x) color = getColor(topPixel) setColor(bottomPixel ,color) show(source) 6.23 The function copyHorseLarger didn’t really work when we copied the pixel twice.

What if we copied it four times? Does that look better?

No it does not look better, since the picture ends up looking with part of it across the rest. def copyHorseLarger2 (): # Set up the source and target pictures src = makePicture("horse.jpg") w = getWidth(src) h = getHeight(src) canvas = makeEmptyPicture(w*2,h*2) srcPixels = getPixels(src) trgPixels = getPixels(canvas) trgIndex = 0 #Now, do the actual copying for pixel in srcPixels: color = getColor(pixel) # Once trgPixel = trgPixels[trgIndex] setColor(trgPixel ,color) trgIndex = trgIndex + 1 # Twice trgPixel = trgPixels[trgIndex] setColor(trgPixel ,color) trgIndex = trgIndex + 1 # Thrice trgPixel = trgPixels[trgIndex] setColor(trgPixel ,color) trgIndex = trgIndex + 1 # Four trgPixel = trgPixels[trgIndex] setColor(trgPixel ,color) trgIndex = trgIndex + 1 show(canvas)

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return canvas 6.24 What do you get from copyHorseLarger you skipped a pixel between every other pixel?

Note: The question should read “if you skipped”.

If you skip a pixel in copying from either the source or the target you’ll end up with a final image with white lines in between the copied pictures.

6.25 Write a function that will scale up just part of the picture. Try making someone’s nose longer. def noseLongerifier (scr, x, y, w, h): canvas = makeEmptyPicture(getWidth(scr), getHeight(scr)) for i in range(0, getWidth(scr)): for j in range(0, getHeight(scr)): p = getPixel(canvas, i, j) p2 = getPixel(scr, i, j) color = getColor(p2) setColor(p, color) sourceX = 0.0 for targetX in range(x,x+w*2): sourceY = 0.0 for targetY in range(y,y+h): px = getPixel(scr,int(sourceX),int(sourceY)) color = getColor(px) setColor(getPixel(canvas ,int(targetX) ,int(targetY)), color) sourceY = sourceY + 1 sourceX = sourceX + 0.5 show(canvas) return canvas Note: This function doubles the width of a past in area, so can be used to lengthen a nose.

6.26 Write a function that will scale down just a part of the picture. Make someone’s head look smaller. def squishTheHead (scr, x, y, w, h): canvas = makeEmptyPicture(getWidth(scr), getHeight(scr)) for i in range(0, getWidth(scr)): for j in range(0, getHeight(scr)): p = getPixel(canvas, i, j) p2 = getPixel(scr, i, j) color = getColor(p2) setColor(p, color)

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sourceX = 0.0 for targetX in range(x,x+int(w/2)): sourceY = 0.0 for targetY in range(y,y+int(h/2)): px = getPixel(scr,int(sourceX),int(sourceY)) color = getColor(px) setColor(getPixel(canvas ,int(targetX) ,int(targetY)), color) sourceY = sourceY + 2 sourceX = sourceX + 2 show(canvas) return canvas Note: This halves the passed in area of the picture.

6.27 Write a function to flip a picture over so that if someone was looking right, they end up looking left. def flipPicture (src): w = getWidth(src) h = getHeight(src) canvas = makeEmptyPicture(w,h) for i in range(0, w): for j in range(0,h): p = getPixel(canvas, w-1-i, j) p2 = getPixel(src, i, j) color = getColor(p2) setColor(p, color) return canvas Note: All you have to do is change the value you grab from if you were to just copy over the image. So the change is from what would be p = getPixel(canvas, x, j) to p = getPixel(canvas, w-1-i, j).

6.28 Write a general crop function that takes a source picture, the start X value, the start Y value, the end X value, and the end Y value. Create and return the new picture and copy just the specified area into the new picture. def crop (src, x1, y1, x2, y2): w = getWidth(src) h = getHeight(src) canvas = makeEmptyPicture(x2-x1,y2-y1) for x in range(x1, x2): for y in range(y1,y2): p = getPixel(canvas, x-x1, y-y1) p2 = getPixel(src, x, y) color = getColor(p2)

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setColor(p, color) return canvas Note: The important lines here are to make sure that you grab from the correct pixels from the canvas. Grabbing the pixels “x” and “y” will not work, as they may be larger than the canvas you’re copying to.

6.29 Write a general scaleUp function that takes in any picture and creates and returns a new picture twice as big using makeEmptyPicture(width,height). def scaleUp (src): w = getWidth(src) h = getHeight(src) canvas = makeEmptyPicture(w*2,h*2) sourceX = 0.0 for targetX in range(0, w*2): sourceY = 0.0 for targetY in range(0,h*2): px = getPixel(src,int(sourceX),int(sourceY)) color = getColor(px) setColor(getPixel(canvas ,int(targetX) ,int(targetY)), color) sourceY = sourceY + 0.5 sourceX = sourceX + 0.5 return canvas 6.30 Write a general scaleDown function that takes in any picture and creates and returns a new picture half as big using makeEmptyPicture(width,height). def scaleDown (src): w = getWidth(src) h = getHeight(src) canvas = makeEmptyPicture(w/2,h/2) sourceX = 0.0 for targetX in range(0, int(w/2)): sourceY = 0.0 for targetY in range(0,int(h/2)): px = getPixel(src,int(sourceX),int(sourceY)) color = getColor(px) setColor(getPixel(canvas ,int(targetX) ,int(targetY)), color) sourceY = sourceY + 2 sourceX = sourceX + 2 return canvas Note: The only differences between this function and the previous one is to increment by 2 instead of 0.5 and to change the canvas size and range sizes to half.

6.31 Modify any of the functions from the last chapter to use a nested loop. Check the

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result to make sure it still does the same thing.

Note: There any many potential options here, but they all require the same approach.

Instead of looping through each pixel, loop through the x values and the y values as two separate loops. The most useful functions to do this in are those that only make changes over a range, as it avoids checking a lot of unnecessary pixels. For example, the removeRedEye function: def removeRedEye(pic,startX,startY,endX,endY,endColor): for x in range(startX, endX): for y in range(startY, endY): px = getPixel(pic, x, y) if (distance(red,getColor(px)) < 165): setColor(px,endColor) 6.32 Write a general function to copy a triangular area from one picture to another.

Note: This question does not specify any restrictions on the triangular area. Students may assume this indicates that they may decide on the triangular area, and therefore may choose to transfer over a right triangle at a certain rotation only. For example, just the triangle made from the top left, bottom left, and top right points of the first picture: #This method assumes the two images have the same height and width def triangleCopy (source, target): h = getHeight(source) w = getWidth(source) for y in range(0,h): for x in range(0,w-1-y , 1): targetPixel = getPixel(target,x,y) sourcePixel = getPixel(source,x,y) color = getColor(sourcePixel) setColor(targetPixel ,color) show(target) Note: Alternatively, students may assume that this question indicates that the function should allow for any triangle. To accomplish that, one would need to use a more general approach (http://stackoverflow.com/questions/2049582/how-to-determine-a-point-in-atriangle). That would lead to a function such as the below (though this function still assumes the points are passed in counter-clockwise. #This method assumes the two images have the same height and width def triangleCopy (source, target, x1, y1, x2, y2, x3, y3): h = getHeight(source) w = getWidth(source) for y in range(0,h):

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for x in range(0,w): b1 = sign(x,y,x1,y1,x2,y2) <0.0 b2 = sign(x,y,x2,y2,x3,y3)<0.0 b3 = sign(x,y,x3,y3,x1,y1)<0.0 if b1==b2 and b2==b3: targetPixel = getPixel(target,x,y) sourcePixel = getPixel(source,x,y) color = getColor(sourcePixel) setColor(targetPixel ,color) show(target) def sign(x1, y1, x2, y2, x3, y3): return (x1 - x3)*(y2-y3)-(x2-x3)*(y1-y3) 6.33 Write a function to mirror the input picture’s leftmost 20 pixels to pixels 20 to 40. def copyOverTwenty (src): w = getWidth(src) h = getHeight(src) for x in range(0, 20): for y in range(0,h): p = getPixel(src, 40-x, y) p2 = getPixel(src, x, y) color = getColor(p2) setColor(p, color) Note: This question is very similar to many we have done before, the key is which pixels it writes to and from. In particular, the range for the first for loop and the line “p = getPixel(src, 40-i, j)”.

6.34 Using nested loops, write a function that reduces red in the top third of a picture and clears blue in the bottom third.

Note: The question does not specify the amount to reduce red by. In this solution, a variable is passed in to determine that amount, but it could also have been hardcoded into the function. def colorAffectThirds (src, redReduction): wThird = int(getWidth(src)/3.0) hThird = int(getHeight(src)/3.0) wTwoThird = int(2.0*(getWidth(src)/3.0)) hTwoThird = int(2.0*(getHeight(src)/3.0)) w = (getWidth(src)) h = (getHeight(src)) for x in range(0, wThird):

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for y in range(0,hThird): p = getPixel(src, x, y) redAmount = getRed(p)-redReduction if redAmount <0: redAmount = 0 setRed(p, redAmount) for x in range(wTwoThird, w): for y in range(hTwoThird,h): p = getPixel(src, x, y) setBlue(p, 0) 6.35 Write a function named makeCollage to create a collage of the same image at least four times fit onto the 7in.x95in.jpg blank JPEG. (You are welcome to add additional images.) One of those four copies can be the original picture. The other three should be modified forms. You can scale, crop, or rotate the image, create a negative of the image, shift or alter colors on the image, and make it darker or lighter. After composing your image, mirror it. You can do this vertically or horizon- tally (or otherwise), in any direction—just make sure that your four base images are still visible after mirroring. Your single function should make all of this happen—all of the effects and compositing must occur from the single function makeCollage. Of course, it is perfectly okay to use other functions, but make it so that a tester of your program need only call setMediaPath(), put all your input pictures in a mediasources directory, and then execute makeCollage() in order to see a collage generated, shown, and returned.

Note: This is an open-ended question. Speaking generally, the important parts of the question are to somehow make four or more different versions of an image, place them onto the specified image, and then mirror the image. A simple, but correct approach is below: def makeCollage (): canvas = makePicture("7in.x95in.jpg") img = makePicture("InsertImageName.jpg") #Get the four different images grayscaleImg = makeGrayscale(img) invertImg = invertImage(img) darkenImg = darkenImage(img) #Copy all four images to the base for x in range(0,getWidth(img)): for y in range(0, getHeight(img)): p = getPixel(img, x, y) pTarget = getPixel(canvas, x, y) setColor(pTarget, getColor(p))

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for x in range(0,getWidth(img)): for y in range(0, getHeight(img)): p = getPixel(grayscaleImg, x, y) pTarget = getPixel(canvas, x+getWidth(grayscaleImg), y) setColor(pTarget,getColor(p)) for x in range(0,getWidth(img)): for y in range(0, getHeight(img)): p = getPixel(invertImg, x, y) pTarget = getPixel(canvas, x, y+getHeight(invertImg)) setColor(pTarget,getColor(p)) for x in range(0,getWidth(img)): for y in range(0, getHeight(img)): p = getPixel(darkenImg, x, y) pTarget = getPixel(canvas, x+getWidth(img), y+getHeight(img)) setColor(pTarget, getColor(p)) #Mirror image and return canvas = mirrorImg(canvas) show(canvas) return canvas def mirrorImg(source): canvas = makeEmptyPicture(getWidth(source), getHeight(source)) for y in range(0,getHeight(source)): for x in range(0,getWidth(source)): topPixel = getPixel(source ,x,y) sourcePixel = getPixel(canvas,getWidth(source)-1-x,y) color = getColor(topPixel) setColor(sourcePixel ,color) return canvas def makeGrayscale(sourceImg): width = getWidth(sourceImg) height = getHeight(sourceImg) canvas = makeEmptyPicture(width,height) for x in range(0, width): for y in range(0,height): p = getPixel(sourceImg, x, y) intensity = (getRed(p)+getGreen(p)+getBlue(p))/3 pTarget = getPixel(canvas, x, y) setColor(pTarget, makeColor(intensity,intensity,intensity)) return canvas def invertImage(sourceImg):

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width = getWidth(sourceImg) height = getHeight(sourceImg) canvas = makeEmptyPicture(width,height) for x in range(0, width): for y in range(0,height): p = getPixel(sourceImg, x, y) pTarget = getPixel(canvas, x, y) setColor(pTarget, makeColor(255-getRed(p),255-getGreen(p),255-getBlue(p))) return canvas def darkenImage(sourceImg): width = getWidth(sourceImg) height = getHeight(sourceImg) canvas = makeEmptyPicture(width,height) for x in range(0, width): for y in range(0,height): p = getPixel(sourceImg, x, y) pTarget = getPixel(canvas, x, y) setColor(pTarget, makeColor(getRed(p)/2,getGreen(p)/2,getBlue(p)/2)) return canvas 6.36 Think about how the grayscale algorithm works. Basically, if you know the luminance of anything visual (e.g., a small image, a letter), you can replace a pixel with that visual element in a similar way to create a collage image. Try implementing this.

You’ll need 256 visual elements of increasing lightness, all of the same size. You can create a collage by replacing each pixel in the original image with one of these visual elements.

Note: This is a complex problem. To avoid passing in 256 unique arguments into a function, an array was used instead. Additionally you will find “createGrayscaleArray” and “makeGrayscaleAmnt” functions included to turn any one image into an array of 256 grayscale images. #Assumes everything in grayscale array has same width/height def makeGrayscaleCollage (source, grayscaleArray): sW = getWidth(source) sH = getHeight(source) collage = makeEmptyPicture(sW*getWidth(grayscaleArray[0]), sH*getHeight(grayscaleArray[0])) for x in range(0, getWidth(source)): for y in range(0,getHeight(source)): p = getPixel(source, x, y) intensity = (getRed(p)+getGreen(p)+getBlue(p))/3 grayScaleimg = grayscaleArray[intensity] widthImg = getWidth(grayScaleimg)

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heightImg = getHeight(grayScaleimg) for xInternal in range(0,widthImg): for yInternal in range(0,heightImg): targetPixel = getPixel(collage, x*widthImg+xInternal, y*heightImg+yInternal) sourcePixel = getPixel(grayScaleimg, xInternal, yInternal) setColor(targetPixel, getColor(sourcePixel)) show(collage) return collage def createGrayscaleArray(sourceImg): imagesArray = [None]*256 for i in range(0,256): imagesArray[i]=makeGrayscaleAmnt(sourceImg, float(i/256.0)) return imagesArray def makeGrayscaleAmnt(sourceImg, grayscaleVal): width = getWidth(sourceImg) height = getHeight(sourceImg) canvas = makeEmptyPicture(width,height) for x in range(0, width): for y in range(0,height): p = getPixel(sourceImg, x, y) intensity = (getRed(p)+getGreen(p)+getBlue(p))/3 newIntensity = float(intensity*grayscaleVal) pTarget = getPixel(canvas, x, y) setColor(pTarget, makeColor(newIntensity,newIntensity,newIntensity)) return canvas 6.37 One of the four functions below generated this picture.

Which one is it?

The answer is option C, the function flip3.

Note: The picture in question has the bottom half of the image mirrored to the top half, and flip3 is the only function to do that. The first function, flip1, mirrors the top half to the bottom, and the other two functions’ effects are not even close to the example image.

6.38 One of the four functions below generated this picture.

Which one is it?

The answer is option C, the function newpic3.

Note: The picture generated has the top right corner from the original picture flipped to the top left corner. The function newpic1 flips the top left corner of the original picture

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into the bottom right of the new one, newpic2 just copies the top left corner from the original, and newpic4 flips the top left corner and spreads it across the entire top half of the output picture.

Chapter 7 7.1 Define the following terms.

1. Clipping The effect when the normal curves of the sound are broken by the limitations of the sample size.

(Source: Chapter 7, Page 229) 2. Normalize An operation that makes a sound as loud as possible via multiplying all samples by a common multiplier (Source: Chapter 7, Page 227-228) 3. Amplitude The distance from the zero point to the greatest pressure (or least pressure), the most important factor in our perception of volume.

(Source: Chapter 7, Page 204) 4. Frequency How often a cycle occurs in a sound file. It is measured in cycles per second or (cps) or Hertz (Hz).

(Source: Chapter 7, Page 205) 5. Rarefactions A decrease in pressure in the air, measured as a negative value against the microphone.

Along with compressions, they are what allows us to hear sounds.

(Source: Chapter 7, Page 204 and 211) 7.2 Write the number −9 in two’s complement. Write the number 4 in two’s complement.

Write the number −27 in two’s complement.

-9 = 11110111 4 = 00000100 -27 = 00011011 -> 11100100 -> 11100101 (Source: Chapter 7, Page 213) 7.3 Open up a Sonogram view in the MediaTools application or a similar sound

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visualization tool say some vowel sounds. Is there a distinctive pattern? Do “oh’s” always sound the same? Do “ah’s”? Does it matter whether you switch people: Are the patterns the same?

Yes, there is a distinct pattern, though there is a lot of variation between people and between different ways of saying the sound. In particular, “oh” depending on its pronunciation generally has a consistent long-shape leading down to a sharp ending, while an “ah” generally looks like a single sharp crest. With different individuals, the patterns look somewhat similar, but may look lower or higher depending on a person’s voice.

7.4 Get a couple of different instruments and play the same note on them in the MediaTools application’s sound editor with the sonogram view open. Are all “C’s” made equal? Do they have the same tones and overtones? Using the MediaTools visualization, can you see the differences between the sounds?

No, not all the “C’s” are equal. You can see the difference between the sounds. In general, instruments with lower ranges actually look “lower”, with the opposite holding true as well.

7.5 Try out a variety of WAV files as instruments, using the piano keyboard in the MediaTools application sound editor. What kinds of recordings work best as instruments?

Note: “Best” is subjective, and therefore there are multiple potential answers to this question. In general though, recordings of real instruments work best.

7.6 The increase volume recipe (Program 93 (page 221)) takes a sound as input. Write a function increaseVolumeNamed that takes a filename as input, then plays the louder sound. def increaseVolumeNamed (fileName): sound = makeSound(fileName) for sample in getSamples(sound): value = getSampleValue(sample) setSampleValue(sample ,value * 2) play(sound) (Source: Chapter 7, Page 215 for makeSound) 7.7 Write a function to increase the volume for all the positive values and decrease the volume for all the negative values. Can you still understand any words in the sound? def makeMorePositive(fileName): sound = makeSound(fileName) for sample in getSamples(sound): value = getSampleValue(sample) if (value>0):

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setSampleValue(sample ,value * 2) else: setSampleValue(sample ,value/2) play(sound) return sound Yes, all words are still understandable.

Note: One could pass in a sound or a filename for this question. The important part is checking whether a value is positive or negative and doing a specific operation based on that.

7.8 Write a function to set all the negative values of a sound to zero. Can you still understand any words in the sound? def removeNegative(fileName): sound = makeSound(fileName) for sample in getSamples(sound): value = getSampleValue(sample) if (value<0): setSampleValue(sample ,0) play(sound) return sound While a bit grainy, all the words are still understandable.

Note: One could pass in a sound or a filename for this question. The important part is checking whether a value is negative and doing a specific operation based on that.

7.9 Write a function to find the smallest value in a sound and print it out. def findSmallestValue(sound): valSmall = 32768 for sample in getSamples(sound): value = getSampleValue(sample) if (value<valSmall): valSmall = value print(valSmall) 7.10 Write a function to count the number of times the value of a sample is 0 and print out the total. def findAllZeroes(sound): timesZero = 0 for sample in getSamples(sound): value = getSampleValue(sample) if (value==0):

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timesZero = timesZero+1 print(timesZero) 7.11 Write a function to set values that are greater than 0 to the maximum positive value (32,767) in a sound, but leave all the negative values the same. Can you still understand any words in the sound? def allPositiveMax(fileName): sound = makeSound(fileName) for sample in getSamples(sound): value = getSampleValue(sample) if (value>0): setSampleValue(sample ,32767) play(sound) While the sound is now exceptionally grainy, the words are all clearly understandable.

Note: One could pass in a sound or a filename for this question. The important part is checking whether a value is positive and doing a specific operation based on that.

7.12 Sometimes people think that the way to increase volume is to add a value (like 1000) to every sample. Write the function fauxIncreaseVolume(sound, increment) to add an input value increment to every sample in an input sound. Try your function with an increment of 1000. Can you hear a difference in the sound? Why or why not? def fauxIncreaseVolume(sound, increment): for sample in getSamples(sound): value = getSampleValue(sample) setSampleValue(sample ,value+increment) play(sound) You cannot hear a real difference in the sound, as we perceive volume as the difference between values, not just the numeric value of the values.

(Source: Chapter 7, Page 204) 7.13 Get a sound. Run increaseVolume on the sound, and then onlyMaximize on the same sound. Get an original copy of the sound. Now, run fauxIncreaseVolume on the new copy, and then onlyMaximize on the output of fauxIncreaseVolume. The sounds will sound different. If the sound had words in it, the words will be much clearer after running fauxIncreaseVolume. Why is that?

The words are much cleaner after running fauxIncreaseVolume then onlyMaximize as fauxIncreaseVolume ensures that the majority of values will be above zero, meaning that after onlyMaximize the values will largely only be 32767, and only occasionally -32768.

In contrast, using increaseVolume then onlyMaximize means that the values will oscillate between 32767 and -32768 much more frequently, leading to far less distinct sounds.

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7.14 Rewrite increase volume (Program 93) so that it takes two inputs: the sound to increase in volume and a filename where the newly louder sound should be stored. Then increase the volume and write the sound out to the name file. You might also try rewriting it so that it takes an input filename instead of the sound, so that inputs are both filenames. def increaseVolume(filenameIn, filenameOut): sound = makeSound(filenameIn) for sample in getSamples(sound): value = getSampleValue(sample) setSampleValue(sample ,value * 2) writeSoundTo(sound, filenameOut) 7.15 Rewrite increase volume (Program 93) so that it takes two inputs: a sound to increase in volume and a multiplier. Use the multiplier as how much to increase the amplitude of the sound samples. Can we use the same function to both increase and decrease the volume? Demonstrate commands that you would execute to do each. def increaseVolume(sound, multiplier): for sample in getSamples(sound): value = getSampleValue(sample) setSampleValue(sample ,value * multiplier) Yes you can use the same method to increase and decrease the volume. Values above 1 will increase the sound, while values below 1, but above zero will decrease the sound.

Increase Sound: increaseVolume(sound, 2) Decrease Sound: increaseVolume(sound, 0.5) 7.16 In Section 7.3.2, we walked through how Program 93 worked. Draw the pictures to show how Program 94 (page 225) works in the same way.

Note: This is simply the images in Section 7.3.2 but with the numbers halved instead of doubled at each step.

Step One: 59

39

16

10

-1

39

16

10

-1

index = 0 value = 0 29 index = 0 value = 59 Step Two:

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29

39

16

10

-1

19

16

10

-1

8

5

0

index = 1 value = 0 29 index = 1 value = 39 End of Step Five: 29

19

index = 4 value = -1 Note: While the function multiplies by 0.5, and therefore one might expect that the end results would be floats, the values of samples must be integers. Therefore instead of 29.5 or 19.5, the value is parsed to an int, giving values of 29 and 19 respectively. This can be checked by running the decreaseVolume function and then exploring the sound afterwards.

7.17 What happens if you increase a volume too far? Explore this by creating a sound object, then increasing the volume once, and again, and again. Does it always keep getting louder? Or does something else happen? Can you explain why?

It keeps getting louder up to a point, but after reaching the max value (positive or negative), a sample cannot be increased any further, meaning that the background noise appears to be getting louder in comparison. This continues until all sample values are at max positive or negative values. At that point, increasing the volume has no effect. This is due to the way in which sounds are stored, that you cannot increase values past 32,767 or -32,767.

7.18 Try sprinkling in some specific values into your sounds.

Note: One can use a function like the below for this entire question: def setSamples(sound, startIndex, endIndex, value): samples = getSamples(sound) for index in range(startIndex, endIndex, 1): setSampleValue(samples[index] ,value) (Source: Chapter 7, Page 226) What happens if you set the value of a few thousand samples in the middle of a sound to 32,767?

The sound sounded largely the same, but for a pair of clicks at the beginning and end of

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the few thousand samples and silence during them.

Or a few thousand to −32,768?

Again the same, but with clicks at the beginning and end of the few thousand samples and silence during them.

Or set the few thousand sample to a bunch of zeroes?

The sound sounds the same, but for those few thousand samples, there will be silence.

Note: For this question and many before, the answers assume you are working with a Mono .wav file. If one works with a Stereo .wav file, they’ll only affect one of its two sound channels, meaning that no matter what they do to the sound object they’ll still be able to hear the original sound channel in one ear. For an explanation of Mono vs Stereo see: http://www.diffen.com/difference/Mono_vs_Stereo

Chapter 8 8.1 Rewrite Program 100 (page 236) so that two input values are provided to the function: the sound and a percentage of how far into the sound to go before changing from increasing to decreasing the volume. def increaseAndDecrease2(sound, percentage): for sampleIndex in range(0,getLength(sound)*percentage): value = getSampleValueAt(sound ,sampleIndex) setSampleValueAt(sound ,sampleIndex ,value * 2) for sampleIndex in range(getLength(sound)*percentage,getLength(sound)): value = getSampleValueAt(sound ,sampleIndex) setSampleValueAt(sound ,sampleIndex ,value * 0.2) 8.2 Rewrite Program 100 so that you normalize the first second of a sound, then slowly decrease the sound in steps of 1/5 for each following second. (How many samples are in a second? getSamplingRate is the number of samples per second for the given sound.) def increaseAndDecrease3(sound): sampleRate = getSamplingRate(sound) largest = -1 #Normalize for sampleIndex in range(0,sampleRate): largest = max(largest ,getSampleValueAt(sound, sampleIndex) ) multiplier = 32767.0 / largest for sampleIndex in range(0,sampleRate): louder = multiplier * getSampleValueAt(sound, sampleIndex)

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setSampleValueAt(sound, sampleIndex,louder) #Decrease by fifths for sampleIndex in range(sampleRate, getLength(sound)): amntToDecreaseBy = (int(sampleIndex)/int(sampleRate))*0.2 newVal = getSampleValueAt(sound, sampleIndex)*(1.0-amntToDecreaseBy) setSampleValueAt(sound, sampleIndex,newVal) Note: The first section is just a translation of Program 97 in Chapter 7, Page 228. The second section “decreases” by making use of integer division, and then multiplying by (1amntToDeceaseBy) as multiplying by just amntToDecreaseBy would have the effect of increasing the values with time. Additionally, its worth noting that this function assumes a sound with a length greater than one, and that with sounds past six seconds in length it will begin to show strange results as you’ll be multiplying by negative values.

8.3 Try rewriting Program 100 so that you have a linear increase in volume to halfway through the sound, then linearly decrease the volume down to zero in the second half. def increaseAndDecrease5(sound): for sampleIndex in range(0,getLength(sound)*0.5): value = getSampleValueAt(sound ,sampleIndex) setSampleValueAt(sound ,sampleIndex ,value * (2*sampleIndex/(getLength(sound)*0.5))) for sampleIndex in range(getLength(sound)*0.5,getLength(sound)): value = getSampleValueAt(sound , sampleIndex) setSampleValueAt(sound ,sampleIndex ,value * (1.0-(sampleIndex getLength(sound)*0.5)/(getLength(sound)*0.5))) 8.4 What happens if you take out the bit of silence added in to the target sound in the splicing example (Program 104 (page 242))? Try it? Can you hear any difference?

No, one cannot hear a difference, since the target sound is initially made up of ten seconds of silence. Therefore, the removal of some seconds of silence has no effect.

8.5 Write a new version of Program 104 to copy “We the” into a new sound and then copy in “united” and finally copy in “people.” Be sure to add 2250 samples with a value of 0 in between the words. Return the new sound. def splicePreamble2(): source = makeSound("preamble10.wav") # This will be the newly spliced sound target = makeEmptySoundBySeconds (5) targetIndex =0 # Where the word "We The" is in the sound for sourceIndex in range (8864 , 18235):

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value = getSampleValueAt(source , sourceIndex) setSampleValueAt(target , targetIndex , value) targetIndex = targetIndex +1 #Silence Second for silence in range(0, 2250): setSampleValueAt(target , targetIndex , 0) targetIndex = targetIndex +1 # Where the word "United" is in the sound for sourceIndex in range (33414 , 40052): value = getSampleValueAt(source , sourceIndex) setSampleValueAt(target , targetIndex , value) targetIndex = targetIndex +1 #Silence Second for silence in range(0, 2250): setSampleValueAt(target , targetIndex , 0) targetIndex = targetIndex +1 # Where the word "People" is in for source for sourceIndex in range(17408, 26726): value = getSampleValueAt(source , sourceIndex) setSampleValueAt(target , targetIndex , value) targetIndex = targetIndex + 1 play(target) return target Note: The location of the “we the” start/end points can be found by making use of the explore() function in the terminal.

8.6 Write a new version of Program 104 to use index array notation (with square brackets).

Note: The only major change for this function is that the samples for both the source and the target, and get and assign the values with different functions. def splicePreamble3(): source = makeSound("preamble10.wav") # This will be the newly spliced sound target = makeEmptySoundBySeconds (5) samples = getSamples(target) sourceSamples = getSamples(source) targetIndex =0 # Where the word "We The" is in the sound

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for sourceIndex in range (8864 , 18235): value = getSampleValue(sourceSamples[sourceIndex]) setSampleValue(samples[targetIndex] , value) targetIndex = targetIndex +1 #Silence Second for silence in range(0, 2250): setSampleValue(samples[targetIndex] , 0) targetIndex = targetIndex +1 # Where the word "United" is in the sound for sourceIndex in range (33414 , 40052): value = getSampleValue(sourceSamples[sourceIndex]) setSampleValue(samples[targetIndex] , value) targetIndex = targetIndex +1 #Silence Second for silence in range(0, 2250): setSampleValue(samples[targetIndex] , 0) targetIndex = targetIndex +1 # Where the word "People" is in for source for sourceIndex in range(17408, 26726): value = getSampleValue(sourceSamples[sourceIndex]) setSampleValue(samples[targetIndex] , value) targetIndex = targetIndex + 1 play(target) return target 8.7 The general functions like Program 108 (page 248) are the kind where the index array notation is really useful. Write reverse, copy, and clip using index array notation. def reverse2(source): target = makeEmptySound(getLength(source)) targetSamples = getSamples(target) sourceSamples = getSamples(source) for sourceIndex in range(0,getLength(source)): sourceValue = getSampleValue(sourceSamples[sourceIndex]) setSampleValue(targetSamples[getLength(source)-1-sourceIndex] ,sourceValue) return target def copy2(source,target,start): targetIndex = start sourceSamples = getSample(source) targetSamples = getSample(target)

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for sourceIndex in range(0,getLength(source)): sourceValue = getSampleValue(sourceSamples[sourceIndex]) setSampleValue(targetSamples[targetIndex] ,sourceValue) ' targetIndex = targetIndex + 1 def clip2(source,start,end): target = makeEmptySound(end - start) sourceSamples = getSamples(source) targetSamples = getSamples(target) for targetIndex in range(0 ,getLength(target)): sourceValue = getSampleValue(sourceSamples[start+targetIndex]) setSampleValue(targetSamples[targetIndex] ,sourceValue) return target 8.8 We think that if we’re going to say “We the united people” in the splice (Program 104), “united” should be really emphasized—really loud. Change the program so that the word “united” is maximally loud (normalized) in the phrase “united people.” def splicePreamble3(): source = makeSound("preamble10.wav") # This will be the newly spliced sound target = makeEmptySoundBySeconds (5) samples = getSamples(target) sourceSamples = getSamples(source) targetIndex =0 # Where the word "We The" is in the sound for sourceIndex in range (8864 , 18235): value = getSampleValue(sourceSamples[sourceIndex]) setSampleValue(samples[targetIndex] , value) targetIndex = targetIndex +1 #Silence Second for silence in range(0, 2250): setSampleValue(samples[targetIndex] , 0) targetIndex = targetIndex +1 #Normalize the "United" word largest = -1 for sourceIndex in range (33414 , 40052): largest = max(largest, getSampleValue(sourceSamples[sourceIndex])) multiplier = 32767.0 / largest # Where the word "United" is in the sound for sourceIndex in range (33414 , 40052): value = multiplier*getSampleValue(sourceSamples[sourceIndex]) setSampleValue(samples[targetIndex] , value)

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targetIndex = targetIndex +1 #Silence Second for silence in range(0, 2250): setSampleValue(samples[targetIndex] , 0) targetIndex = targetIndex +1 # Where the word "People" is in for source for sourceIndex in range(17408, 26726): value = getSampleValue(sourceSamples[sourceIndex]) setSampleValue(samples[targetIndex] , value) targetIndex = targetIndex + 1 play(target) return target 8.9 Try using a stopwatch to time the execution of the programs in this chapter. Time from hitting return on the command until the next prompt appears. What is the relationship between execution time and the length of the sound? Is it a linear relationship (i.e., longer sounds take longer to process and shorter sounds take less time to process)?

Or is it something else? Compare the individual programs. Does normalizing a sound take longer than raising (or lowering) the amplitude a constant amount? How much longer? Does it matter whether the sound is longer or shorter?

The precise amount of time will depend on the computer’s processing power on which the algorithms are run on. However, in general longer sounds run on the same function take longer. Functions that involve iterating more also take longer. This means that normalizing takes the longest out of the programs in this chapter as it involves iterating over the entire length of the sound twice.

8.10 Make an audio collage. Make it at least 5 seconds long, and include at least two different sounds (i.e., they come from different files). Make a copy of one of those different sounds and modify it using any of the techniques described in this chapter (i.e., mirroring, splicing, volume manipulations). Splice together the original two sounds and the modified sound to make the complete collage.

Note: This example specifically makes use of “preamble10.wav” and “the.wav”, but as long as the end result is over 5 seconds, any sounds may be used. def collage(): source = makeSound("preamble10.wav") source2 = makeSound("the.wav") modified = makeEmptySound(getLength(source2)) modifiedSamples = getSamples(modified) source2Samples = getSamples(source2) #Mirror Modified

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for sourceIndex in range(0, getLength(source2)): sourceValue = getSampleValue(source2Samples[sourceIndex]) setSampleValue(modifiedSamples[getLength(source2)-1-sourceIndex] ,sourceValue) #Copy them all over target = makeEmptySound((getLength(source)+getLength(source2)+getLength(modified))) targetIndex = 0 targetSamples = getSamples(target) sourceSamples=getSamples(source) #Copy Source 2 for index in range(0, getLength(source2)): sourceValue = getSampleValue(source2Samples[index]) setSampleValue(targetSamples[targetIndex] ,sourceValue) targetIndex = targetIndex+1 #Copy Source 1 for index in range(0, getLength(source)): sourceValue = getSampleValue(sourceSamples[index]) setSampleValue(targetSamples[targetIndex] ,sourceValue) targetIndex = targetIndex+1 #Copy Modified for index in range(0, getLength(modified)): sourceValue = getSampleValue(modifiedSamples[index]) setSampleValue(targetSamples[targetIndex] ,sourceValue) targetIndex = targetIndex+1 play(target) return target 8.11 Compose a sentence that no one ever said by combining words from other sounds into a grammatically correct new sound. Write a function named audioSentence to generate a sentence out of individual words. Use at least three words in your sentence.

You can use the words in the mediasource folder from the Web site or record your own words. Be sure to include a tenth (1/10) of a second pause between the words. (Hint 1: Remember that zeroes for the sample values generate silence. Hint 2: Remember that the sampling rate is the number of samples per second. From there, you should be able to figure out how many samples need to be made zero to generate a tenth of a second of silence.) Be sure to access your sounds in your Media Folder using getMediaPath so that it will work for users of your program as long as they first execute setMediaPath. def audioSentence(): source1 = makeSound("trying.wav") source1Samples = getSamples(source1) source2 = makeSound("to.wav")

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source2Samples = getSamples(source2) source3 = makeSound("impress.wav") source3Samples = getSamples(source3) source4 = makeSound("the.wav") source4Samples = getSamples(source4) source5 = makeSound("pig.wav") source5Samples = getSamples(source5) s1L = getLength(source1) s2L = getLength(source2) s3L = getLength(source3) s4L = getLength(source4) s5L = getLength(source5) tenthOfSecondLength = getSamplingRate(source1)/10 tenthOfSecondLength = int(tenthOfSecondLength) target = makeEmptySound(s1L+s2L+s3L+s4L+s5L+4*tenthOfSecondLength) targetSamples = getSamples(target) targetIndex=0 #Source 1 Copy Over for index in range(0, getLength(source1)): sourceValue = getSampleValue(source1Samples[index]) setSampleValue(targetSamples[targetIndex] ,sourceValue) targetIndex = targetIndex+1 for silenceIndex in range(0, tenthOfSecondLength): setSampleValue(targetSamples[targetIndex] ,0) targetIndex = targetIndex+1 #Source 2 Copy Over for index in range(0, getLength(source2)): sourceValue = getSampleValue(source2Samples[index]) setSampleValue(targetSamples[targetIndex] ,sourceValue) targetIndex = targetIndex+1 for silenceIndex in range(0, tenthOfSecondLength): setSampleValue(targetSamples[targetIndex] ,0) targetIndex = targetIndex+1 #Source 3 Copy Over for index in range(0, getLength(source3)): sourceValue = getSampleValue(source3Samples[index]) setSampleValue(targetSamples[targetIndex] ,sourceValue) targetIndex = targetIndex+1 for silenceIndex in range(0, tenthOfSecondLength): setSampleValue(targetSamples[targetIndex] ,0) targetIndex = targetIndex+1

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#Source 4 Copy Over for index in range(0, getLength(source4)): sourceValue = getSampleValue(source4Samples[index]) setSampleValue(targetSamples[targetIndex] ,sourceValue) targetIndex = targetIndex+1 for silenceIndex in range(0, tenthOfSecondLength): setSampleValue(targetSamples[targetIndex] ,0) targetIndex = targetIndex+1 #Source 5 Copy Over for index in range(0, getLength(source5)): sourceValue = getSampleValue(source5Samples[index]) setSampleValue(targetSamples[targetIndex] ,sourceValue) targetIndex = targetIndex+1 play(target) return target 8.12 Write a function to add 1 second of silence to the beginning of a sound. It should take the sound as input, create the new empty target sound, then copy the original sound starting after the first second in the target.

Note: The sampling rate has to be of type int if its going to work with index array notation. def addStartSilence(sound): sampleRate = int(getSamplingRate(sound)) target = makeEmptySound(sampleRate+getLength(sound)) targetSamples = getSamples(target) sourceSamples = getSamples(sound) for index in range(0, getLength(sound)): sourceValue = getSampleValue(sourceSamples[index]) setSampleValue(targetSamples[sampleRate+index] ,sourceValue) return target 8.13 Search the Web for songs that have hidden messages that you can hear when you reverse the sound.

Note: The Wikipedia article “List of backmasked messages” has a number of excellent, well-cited examples. However, it is somewhat R-rated. http://en.wikipedia.org/wiki/List_of_backmasked_messages Examples: “Rain” by The Beatles and “Michael” by Franz Ferdinand 8.14 Write a function that splices together words and music.

Note: This question does not specify how to splice together the words and music.

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However, a simple way that emulates a “techno” song would be to repeatedly splice a phrase into a piece of music. The function below accomplishes this, however one could also make use of a less general approach. #music is the base, sound is the phrase to copy into it #interval is the interval in seconds to copy it def addStartSilence(sound, music, interval): target = makeEmptySound(getLength(music)) targetSamples = getSamples(target) soundSamples = getSamples(sound) musicSamples = getSamples(music) #First copy the music to the target for index in range(0, getLength(music)): sourceValue = getSampleValue(musicSamples[index]) setSampleValue(targetSamples[index] ,sourceValue) #Then copy the phrase into the musical at the regular interval for musicIndex in range(0, getLength(music), getSamplingRate(music)*interval): for index in range(0, getLength(sound)): sourceValue = getSampleValue(soundSamples[index]) setSampleValue(targetSamples[musicIndex+index] ,sourceValue) return target 8.15 Write a function that interleaves two sounds. It starts with 2 seconds of the first sound and then 2 seconds of the second sound. Then it continues with the next 2 seconds of the first sound and the next 2 seconds of the second sound and so on until both sounds have been fully copied to the target sound.

Note: For this answer, one cannot assume the two sounds will be the same length, or that they’ll go evenly into 2 second chunks, therefore it’s necessary to check whether one sound has already been “used up” in order to avoid a run time error. def interleaveSounds(sound, sound2): target = makeEmptySound(getLength(sound) + getLength(sound2)) targetSamples = getSamples(target) soundSamples = getSamples(sound) soundIndex = 0 sound2Samples = getSamples(sound2) sound2Index = 0 sectionLength = int(getSamplingRate(target)*2) for index in range(0, getLength(target)): section = int(index)/sectionLength

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if section %2==0: if soundIndex<getLength(sound): sourceValue = getSampleValue(soundSamples[soundIndex]) setSampleValue(targetSamples[index] ,sourceValue) soundIndex = soundIndex+1 elif sound2Index<getLength(sound2): sourceValue = getSampleValue(sound2Samples[sound2Index]) setSampleValue(targetSamples[index] ,sourceValue) sound2Index = sound2Index+1 else: if sound2Index<getLength(sound2): sourceValue = getSampleValue(sound2Samples[sound2Index]) setSampleValue(targetSamples[index] ,sourceValue) sound2Index = sound2Index+1 elif soundIndex<getLength(sound): sourceValue = getSampleValue(soundSamples[soundIndex]) setSampleValue(targetSamples[index] ,sourceValue) soundIndex = soundIndex+1 return target 8.16 Write a function called erasePart to set all the samples in the 2nd second of thisisatest.wav to 0’s—essentially, making the 2nd second go silent. (Hint: Remember that getSamplingRate(sound) tells you the number of samples in a single second in a sound.) Play and return the partially erased sound. def erasePart(): sound = makeSound("thisisatest.wav") soundSamples = getSamples(sound) sampleRate = getSamplingRate(sound) for index in range(sampleRate, sampleRate*2): setSampleValue(soundSamples[index] ,0) play(sound) return sound 8.17 Can you write a function that finds the silence between words? What should it return?

Note: There are many possibilities in terms of what the function should return. At this point with what one has learned from the book thus far, the best solution would be to make use of a string that described where the silence segments were. Additionally, it’s

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not necessary to write a function for this section, though one can. Only the approach needs to be described.

Yes, one can write a function that finds the silence between words by finding stretches of 0 values. One should return a string value describing the start and end points of the segments of silence.

8.18 Write a function to increase the volume on the passed sound just between the passed start and end index.

Note: The function does not specify by what amount to increase the volume, therefore anything from multiplying the value by a number greater than one to normalizing the segment would be appropriate. def increaseVolumeBetween(sound, startIndex, endIndex): soundSamples = getSamples(sound) for index in range(startIndex, endIndex): sourceValue = 2*getSampleValue(soundSamples[index]) setSampleValue(soundSamples[index], sourceValue) 8.19 Write a function to reverse part of the passed sound just between the passed start and end index.

Note: In order to reverse part of the passed in sound, and not a copy of the sound, we need to copy out the entirety of the non-reverse section in order to avoid overwriting half of it as we reverse. def reverseBetween(sound, startIndex, endIndex): soundSamples = getSamples(sound) target = makeEmptySound(endIndex-startIndex) targetSamples = getSamples(target) for index in range(startIndex, endIndex): sourceValue = getSampleValue(soundSamples[index]) setSampleValue(targetSamples[index-startIndex], sourceValue) for index in range(startIndex, endIndex): sourceValue = getSampleValue(targetSamples[index-startIndex]) setSampleValue(soundSamples[endIndex-1-(index-startIndex)], sourceValue) 8.20 Write a function mirrorBackToFront that mirrors the second half of a sound onto the first half. def mirrorBackToFront(sound): soundSamples = getSamples(sound)

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for index in range(0, getLength(sound)/2): sourceValue = getSampleValue(soundSamples[getLength(sound)-1-index]) setSampleValue(soundSamples[index], sourceValue)

8.21 Write a function mirrorFrontToBack that mirrors the first half of a sound onto the second half. def mirrorFrontToBack (sound): soundSamples = getSamples(sound) for index in range(0, getLength(sound)/2): sourceValue = getSampleValue(soundSamples[index]) setSampleValue(soundSamples[getLength(sound)-1-index], sourceValue) 8.22 Write a function called reverseSecondHalf that takes a sound as input, then reverses just the second half of the sound and returns the result. For example, if the sound said “MarkBark,” the returned sound should say “MarkkraB.” Note: We can rework our answer to question 19 to answer this one. def reverseSecondHalf(sound): startIndex = getLength(sound)/2 endIndex=getLength(sound) soundSamples = getSamples(sound) target = makeEmptySound(endIndex-startIndex) targetSamples = getSamples(target) for index in range(startIndex, endIndex): sourceValue = getSampleValue(soundSamples[index]) setSampleValue(targetSamples[index-startIndex], sourceValue) for index in range(startIndex, endIndex): sourceValue = getSampleValue(targetSamples[index-startIndex]) setSampleValue(soundSamples[endIndex-1-(index-startIndex)], sourceValue) 8.23 There is a Python keyword called global. Learn what it does, then change fun1 from the last section to access and change a variable c in the Command Area. (You can change how you define the variable in the Command Area, too.)

(Source: Chapter 10, Pages 298-299) def fun1(): global a a = 12

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c= "George" print a,c Then the terminal input/output should look like: >>> a = "Hello" >>> fun1() 12 George >>> a 12

Chapter 9 9.1 What are each of the following: 1. MIDI MIDI stands for Musical Instrument Digital Interface, its an encoding that captures how a piece of music is played, not what it sounds like.

(Source: Chapter 9, Page 274) 2. MP3 A file-type for audio and video storage based on the MPEG-3 standard.

(Sound: Chapter 9, Page 273) 3. Analog A type of recoding of audio data used in records that captures all frequencies of the sounds, even the ones humans can’t hear, and records continuously as opposed to making samples.

(Source: Chapter 9, Pages: 273-274) 4. Amplitude The “height” of the waves of a sound from the baseline.

(Source: Chapter 9, Pages 266-267) 5. Sampling rate The numbers of samples in one second.

(Source: Chapter 9, Page 266) 9.2 What is the difference between lossless compression and lossy compression? Which type of sound files use what type of compression?

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Both only encode the differences between samples instead of sample values, but lossless compression keeps even the differences humans can’t hear while lossy compression does not. WAV and AIFF files use lossless compression while MP3 files use both.

(Source: Chapter 9, Pages 273-274) 9.3 Rewrite the echo function (Program 111 (page 258)) to generate two echoes back, each delay samples previous. (Hint: Start your index loop at 2*delay + 1, then access one echo sample at index-delay and another at index - 2*delay.) def echo2(delay ,s1): s2 = duplicateSound(s1) for index in range(2*delay+1 , getLength(s1)): # set delay value to original value + delayed value * .6 echoSample = 0.6*getSampleValueAt(s2, index-delay) echoSample2 = 0.6*getSampleValueAt(s2, index-2*delay) comboSample = getSampleValueAt(s1,index) + echoSample+echoSample2 setSampleValueAt(s1, index,comboSample) play(s1) return s1 9.4 Write a general blend function that takes the two sounds to blend as input and returns a new sound. def blend2(sound ,sound2): canvas = makeEmptySoundBySeconds(3) for index in range(0, 20000): soundSample = getSampleValueAt(sound,index) setSampleValueAt(canvas ,index ,soundSample) for index in range (0 ,20000): soundSample = getSampleValueAt(sound,index+20000) sound2Sample=getSampleValueAt(sound2,index) newSample = 0.5* soundSample + 0.5* sound2Sample setSampleValueAt(canvas ,index+20000,newSample) for index in range (20000 ,40000): sound2Sample = getSampleValueAt(sound2,index) setSampleValueAt(canvas ,index+20000,sound2Sample) play(canvas) return canvas 9.5 Generalize your general blend function even more. Take in the number of samples to use from the first sound before the blend begins and the number of samples to blend.

Note: The question does not specify the number of samples to use for the second sound, so the function below just uses the same number for the first sound. However, this is not required.

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Additionally, this function needs to change the line that instantiates the canvas regardless of the value used in order to throw an error when it attempts to access an index that isn’t there. def blend3(sound ,sound2, numSamples, numBlend): canvas = makeEmptySound(numSamples*2+numBlend) for index in range(0, numSamples): soundSample = getSampleValueAt(sound,index) setSampleValueAt(canvas ,index ,soundSample) for index in range (0 ,numBlend): soundSample = getSampleValueAt(sound,index+numSamples) sound2Sample=getSampleValueAt(sound2,index) newSample = 0.5* soundSample + 0.5* sound2Sample setSampleValueAt(canvas ,index+numSamples,newSample) for index in range (numBlend ,numSamples+numBlend): sound2Sample = getSampleValueAt(sound2,index) setSampleValueAt(canvas ,(index+numSamples),sound2Sample) play(canvas) return canvas 9.6 How long is a sound compared to the original when it’s been frequency doubled (Program 116 (page 261))? How long is a sound compared to the original when only every fourth sound value is copied into the target sound?

With the frequency doubled, the sound is half its original length plus one, as one can see from the first line of the “double” function. As one might expect, following this same line, copying every fourth value creates a sound of a quarter of length one in terms of the original.

9.7 Write a function to input a sound, then create a canvas sound of the same length.

Copy samples from the input into the canvas every other position, i.e., copy from index 0 in the input into the canvas at index 0, then copy from index 2 (skipping index 1) in the input into the canvas at index 1. What do you hear in the canvas sound? Same sound?

Faster? Slower?

The sound is the same speed, but it sounds much “grainier” or lower quality. This makes sense as we’ve essentially copied less samples for the same sound. def alternateCopy(source): target = makeEmptySound(getLength(source)) for index in range(0, getLength(source), 2): sourceValue = getSampleValueAt(source ,index) setSampleValueAt(target, index , sourceValue) play(target) return target

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9.8 Write a function to input a sound, then create a canvas sound of the same length.

Copy samples from the input into the canvas every third position, i.e., copy from index 0 in the input into the canvas at index 0, then copy from index 3 (skipping index 1 and 2) in the input into the canvas at index 3. What do you hear in the canvas sound? Same sound?

Faster? Slower?

Again the sound is the same length, but even more grainy this time. def alternateCopy2(source): target = makeEmptySound(getLength(source)) for index in range(0, getLength(source), 3): sourceValue = getSampleValueAt(source ,index) setSampleValueAt(target, index , sourceValue) play(target) return target 9.9 Write a function that will input two sounds. Create a new sound with one half of the first sound, then add the two sounds together for the length of the two sounds, and then add the second half of the second sound. This is easiest to do if the sounds have the same length.

Note: While this is easiest to do if the sounds have the same length, the function below can handle sounds of different lengths via the two if statements in the mid loop.

However, this is not required to answer this question. Additionally, the question does not specify how to “add” the two sounds together, which means an answer could just add both values together. To avoid something too loud, the function below blends the two sounds, but this is not a requirement. def addSounds(sound ,sound2): maxLength = max(getLength(sound), getLength(sound2)) canvas=makeEmptySound(getLength(sound)/2+getLength(sound2)/2+maxLength) for index in range(0, getLength(sound)/2): soundSample = getSampleValueAt(sound,index) setSampleValueAt(canvas ,index ,soundSample) for index in range (0 ,maxLength): soundSample = 0 if index<getLength(sound): soundSample = getSampleValueAt(sound,index) sound2Sample = 0 if index<getLength(sound2): sound2Sample=getSampleValueAt(sound2,index) newSample = 0.5* soundSample + 0.5* sound2Sample setSampleValueAt(canvas ,index+getLength(sound)/2,newSample) for index in range (0 ,getLength(sound2)/2): sound2Sample = getSampleValueAt(sound2,index) setSampleValueAt(canvas ,(index+getLength(sound)/2+maxLength),sound2Sample)

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play(canvas) return canvas 9.10 Write a function that will blend three sounds together. Start with part of the first sound, then a blend of sound1 and sound2, and then a blend of sound2 and sound3, and end with the rest of sound3. def blendThree(sound1,sound2, sound3): maxL = max(getLength(sound1), getLength(sound2)) maxL2 = max(getLength(sound2), getLength(sound3)) canvas=makeEmptySound(maxL+maxL2+getLength(sound1)+getLength(sound3)) #Copy all of sound one for index in range(0, getLength(sound1)): soundSample = getSampleValueAt(sound1,index) setSampleValueAt(canvas ,index ,soundSample) #Blend sound1 and sound2 for index in range (0 ,maxL): soundSample = 0 if index<getLength(sound1): soundSample = getSampleValueAt(sound1,index) sound2Sample = 0 if index<getLength(sound2): sound2Sample=getSampleValueAt(sound2,index) newSample = 0.5* soundSample + 0.5* sound2Sample setSampleValueAt(canvas ,index+getLength(sound1),newSample) #Blend sound2 and sound3 for index in range (0 ,maxL2): soundSample = 0 if index<getLength(sound2): soundSample = getSampleValueAt(sound2,index) sound2Sample = 0 if index<getLength(sound3): sound2Sample=getSampleValueAt(sound3,index) newSample = 0.5* soundSample + 0.5* sound2Sample setSampleValueAt(canvas ,index+getLength(sound1)+maxL,newSample) for index in range (0 ,getLength(sound3)): sound2Sample = getSampleValueAt(sound3,index) setSampleValueAt(canvas ,(index+getLength(sound)+maxL+maxL2),sound2Sample) play(canvas) return canvas

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9.11 Blend in some words over some music. Start with the music at 75% and the words at 25% and gradually make the words 75% and the music 25%.

Note: If the function assumes the words and music are of the same length, then it can look like the below. Otherwise, the answer would need to specifically check for the current length as in the answer to question 10. def blendMusic(sound,music): maxL = max(getLength(sound), getLength(music)) canvas=makeEmptySound(maxL) #Blend sound1 and sound2 for index in range (0 ,maxL): #This value will range from 0 to 1 multiple = index/maxL soundSample = getSampleValueAt(sound,index)*(0.25+0.5*multiple) musicSample=getSampleValueAt(music,index)*(0.75-0.5*multiple) newSample = soundSample + musicSample setSampleValueAt(canvas ,index,newSample) play(canvas) return canvas

9.12 Write a function that inputs a frequency, a maximum amplitude, and length in seconds. Create two sounds, one a square and one a triangle, using the same inputs. Add the sounds together. What do you get?

Note: The easiest way to create this function is to just call the squareWave (Chapter 9, Pages 269-270) and triangleWave (Chapter 9, Pages 271-272) functions individually.

You get a series of shapes halfway between a triangle and a square.

def combineShapeSounds(freq, amplitude, seconds):

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square = squareWave(freq, amplitude, seconds) triangle = triangleWave(freq, amplitude, seconds) canvas = makeEmptySoundBySeconds(seconds) for index in range(0, getLength(canvas)): triSample = getSampleValueAt(triangle, index) squareSample = getSampleValueAt(square, index) newSample = triSample + squareSample setSampleValueAt(canvas, index, newSample) return canvas 9.13 Write a function that inputs a frequency, a maximum amplitude, a percentage of blend (e.g., 0.25 to represent 25%), and length in seconds. Create two sounds, one a square and one a triangle, using the same inputs. Add the sounds together, with the blend percentage of the square and 100—blend of the triangle. How does the sound change if you try 0.25, 0.5, and 0.75 as the blend percentages?

The sounds don’t sound all that different with different blend percentages, they largely just sound louder the larger the percentage gets. However, the sound also does sound more “warbly” with the lower blend percentages, as there’s more of a difference between the two sounds. def combineShapeSounds(freq, amplitude, percentBlend, seconds): square = squareWave(freq, amplitude, seconds) triangle = triangleWave(freq, amplitude, seconds) canvas = makeEmptySoundBySeconds(seconds) for index in range(0, getLength(canvas)): triSample = getSampleValueAt(triangle, index) squareSample = getSampleValueAt(square, index)*percentBlend newSample = triSample + squareSample setSampleValueAt(canvas, index, newSample) play(canvas) return canvas 9.14 Write a function to change the frequency of a sound 10 times—five times lower than the original frequency, and five times higher.

Note: The function does not specify the amount to change the frequency by, therefore shifting it by any amount between one and zero five times then any amount greater than one five times will work. The easiest way to do this is to make use of the “halve” (Chapter 9, Page 262) and “double” (Chapter 9, Page 261) functions from this chapter.

However, this will be very slow.

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def raiseThenLower(sound): #Lower Five Times sound = halve(sound) sound = halve(sound) sound = halve(sound) sound = halve(sound) sound = halve(sound) #Raise Five Times sound = double(sound) sound = double(sound) sound = double(sound) sound = double(sound) sound = double(sound) return sound 9.15 Create a new version of the shift function that creates the target to be as big as the resulting sound should be. So if the factor is less than one it would create a larger sound and if greater than one a smaller sound. def shift(source,factor): len = 0 if factor>1: len = int(getLength(source)/factor) elif factor>0 and factor<1: len = int(getLength(source)/factor + 1) target = makeEmptySound(len) sourceIndex = 0 for targetIndex in range(0, len): sourceValue = getSampleValueAt(source,int(sourceIndex)) setSampleValueAt(target , targetIndex , sourceValue) sourceIndex = sourceIndex + factor if (sourceIndex >= getLength(source)): sourceIndex = 0 play(target) return target 9.16 Does the shift function work with a factor of 0.3? If it doesn’t, can you fix it to copy each source value three times into the target?

No, due to rounding when parsing the value to an int, it fluctuates between copying each sound value three or four times into the target.

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It is possible to fix by just using a different factor, 0.3 is not actually representative of lowering the frequency by three as it is closer to three-tenths. Making use of a value of 0.3333333 will copy each source value three times into the target.

9.17 Hip-hop DJs spin turntables back and forth so that sections of sound are played forwards and backwards quickly. Try combining backwards play (Program 108 (page 248)) and frequency shifting (Program 116 (page 261)) to get the same effect. Play a second of a sound quickly forward, then quickly backward, two or three times. (You might have to move faster than just double the speed.) def djShift(sound): sampleRate = getSamplingRate(sound) #We're gonna have six seconds with a four times frequency canvas = makeEmptySound(int(((sampleRate)*1.5)+4)) targetIndex = 0 for i in range(0, 6): if i %2==0: for index in range(0, sampleRate, 4): sourceValue = getSampleValueAt(sound, index) setSampleValueAt(canvas, targetIndex, sourceValue) targetIndex= targetIndex+1 else: for index in range(0, sampleRate, 4): sourceValue = getSampleValueAt(sound, getLength(sound)-1-index) setSampleValueAt(canvas, targetIndex, sourceValue) targetIndex= targetIndex+1 play(canvas) return canvas 9.18 Consider changing the if block in the frequency shift recipe (Program 119 (page 264)) to sourceIndex = sourceIndex - getLength(source).

What’s the difference from just setting the sourceIndex to 0? Is this better or worse?

Why? This is a very minimal difference. As it was previously, if the sourceIndex grew too large it would be returned to 0, essentially the sound would start over again from the beginning. With this way sourceIndex is instead set the amount over source’s length it currently is. For example, if you had a sound of length 3001 and you were increasing by a factor of 3, sourceIndex would be set to 3003 because of the line “sourceIndex = sourceIndex+factor” and then end up at index 2 (3003-3001) instead of index 0.

One could argue either way in terms of this approaching being better or worse. You could suggest that it is better as the indexes all are a consistent “distance” apart. So in the last example, going from the last index we recorded (3000) to 2, a value of distance three if

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you loop around. However, one could also see this as a negative as it avoids the 0 value, and would lead to slightly different iterations of the sound each time as you don’t start at the same place.

9.19 If you use the shifting recipe (Program 119) with a factor of 2.0 or 3.0, you’ll get the sound repeated or even triplicated. Why? Can you fix it? Write shiftDur that takes a number of samples (or even seconds) to play the sound.

You get the sound repeated or triplicated as the higher frequency sound takes up less time, but still has to fill up the full length of the original sound as the function is written.

To only make it play once one could either stop copying the original values after one iteration, or constrain the length of the new sound.

Note: The last sentence of the question could be interpreted in a number of ways. It could be read to indicate that a function should be created that just repeated the sound for a number of seconds, as the below does. def shift2(source, factor, length): target = makeEmptySound(length) sourceIndex = 0 for targetIndex in range(0, getLength(target)): sourceValue = getSampleValueAt(source,int(sourceIndex)) setSampleValueAt(target , targetIndex , sourceValue) sourceIndex = sourceIndex + factor if (sourceIndex >= getLength(source)): sourceIndex = sourceIndex - getLength(source) play(target) return target However, the sentence could alternatively be translated to indicate that the new sound should take up the amount of time indicated and that a factor should be determined from these values, such as the below. def shift2(source, length): target = makeEmptySound(int(length)) sourceIndex = 0 factor = (getLength(source)/length) for targetIndex in range(0, getLength(target)): sourceValue = getSampleValueAt(source,int(sourceIndex)) setSampleValueAt(target , targetIndex , sourceValue) sourceIndex = sourceIndex + factor if (sourceIndex >= getLength(source)): sourceIndex = sourceIndex - getLength(source) play(target)

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return target 9.20 Using the sound tools, figure out the characteristic pattern of different instruments.

For example, pianos tend to have a pattern the opposite of what we created- the amplitudes decrease as we get to higher sine waves. Try creating a variety of patterns and see how they sound and how they look.

Note: This question simply requires an answer with a few examples of sounds and patterns.

A violin even when playing the same note as a piano or synthesizer has a pattern of sound with a variety of different waves. The human voice looks much more similar to a violin than to a piano, but with the individual waves having a much higher contrast. An acoustic guitar looks a bit like a mix between a violin and a piano 9.21 When musicians work with additive synthesis, they will often wrap envelopes around the sounds, and even around each added sine wave. An envelope changes the amplitude over time—it might start out small, then grow (rapidly or slowly), then hold at a certain value during the sound, and then drop before the sound ends. That kind of pattern is sometimes called the attack-sustain-decay (ASD) envelope. Pianos tend to attack quickly, then decay quickly. Flutes tend to attack slowly and sustain as long as you want. Try implementing that for the sine and square wave generators.

Note: It is unclear what “that” refers to in the last sentence of the question. Due to its proximity, the best assumption is that it refers to the previous sentence, especially given that that the sine and square generations can sustain for “as long as you want”. def sineWave(freq,amplitude,secs): # Get a blank sound buildSin = makeEmptySoundBySeconds(secs) # Set sound constant sr = getSamplingRate(buildSin) interval = 1.0/freq samplesPerCycle = interval * sr maxCycle = 2 * pi for pos in range (0,getLength(buildSin)): amp = amplitude if pos<500: amp = (pos/500.0)*amplitude rawSample = sin((pos / samplesPerCycle) * maxCycle) sampleVal = int(amp*rawSample) setSampleValueAt(buildSin ,pos,sampleVal) return buildSin def squareWave(freq, amplitude, seconds): # Get a blank sound

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square = makeEmptySoundBySeconds(seconds) # Set sound constant sr = getSamplingRate(square) # sampling rate #Set music constants samplingRate = getSamplingRate(square) # Build tools for this wave # seconds per cycle: make sure floating point interval = 1.0 * seconds / freq # creates floating point since interval is fl point samplesPerCycle = interval * samplingRate # we need to switch every half-cycle samplesPerHalfCycle = int(samplesPerCycle / 2) sampleVal = amplitude s=1 i=1 for s in range (0, getLength(square)): amp = sampleVal if s<500: amp = (s/500.0)*sampleVal # if end of a half-cycle if (i > samplesPerHalfCycle): # reverse the amplitude every half-cycle sampleVal = sampleVal * -1 # and reinitialize the half-cycle counter i=0 setSampleValueAt(square,s,amp) i=i+1 return(square) 9.22 Create a function to play your school’s fight song using MIDI. Note: Below is the Georgia Tech Fight Song. Specifically it is the most famous section.

Many school fight songs have a large number of verses that are not required for an answer to this question. def fightsong(): quarterNote = 300 intensity = 127 playNote(67, int(quarterNote), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(63, int(quarterNote), intensity) playNote(63, int(quarterNote/2.0), intensity)

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playNote(63, int(quarterNote), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(67, int(quarterNote), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(63, int(quarterNote/2.0), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(63, int(quarterNote), intensity) playNote(62, int(quarterNote/2.0), intensity) playNote(63, int(quarterNote*2.5), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(68, int(quarterNote/2.0), intensity) playNote(70, int(quarterNote/2.0), intensity) playNote(70, int(quarterNote/2.0), intensity) playNote(70, int(quarterNote/2.0), intensity) playNote(70, int(quarterNote/2.0), intensity) playNote(70, int(quarterNote/2.0), intensity) playNote(70, int(quarterNote/2.0), intensity) playNote(70, int(quarterNote/2.0), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(65, int(quarterNote), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(65, int(quarterNote*2.5), intensity) playNote(70, int(quarterNote/2.0), intensity) playNote(72, int(quarterNote), intensity) playNote(68, int(quarterNote/2.0), intensity) playNote(72, int(quarterNote), intensity) playNote(68, int(quarterNote/2.0), intensity)

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playNote(72, int(quarterNote/2.0), intensity) playNote(75, int(quarterNote*2.0), intensity) playNote(72, int(quarterNote/2.0), intensity) playNote(70, int(quarterNote), intensity) playNote(72, int(quarterNote/2.0), intensity) playNote(70, int(quarterNote), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(70, int(quarterNote*1.5), intensity) playNote(67, int(quarterNote), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(63, int(quarterNote), intensity) playNote(63, int(quarterNote/2.0), intensity) playNote(63, int(quarterNote), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(67, int(quarterNote), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(63, int(quarterNote/2.0), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(65, int(quarterNote/2.0), intensity) playNote(63, int(quarterNote), intensity) playNote(62, int(quarterNote/2.0), intensity) playNote(63, int(quarterNote*2), intensity) 9.23 The Web site https://musopen.org/ has copyright-free sheet music. Take any one of those songs and translate it into MIDI notes, and write a function to play it.

(Source: http://newt.phys.unsw.edu.au/jw/notes.html for translating music to MIDI note numbers) Note: One of the shortest pieces on musopen is Mozart’s Andante in C. However it, like many of the pieces on the website, has two “tracks” to lines of music going at the same time. Since with the knowledge thus presented in the book it’d be impossible to play two notes at once, an answer only needs to translate one track. def classicsong(): quarterNote = 400 intensity = 127 playNote(67, int(quarterNote/2.0), intensity)

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playNote(72, int(quarterNote/4.0), intensity) playNote(67, int(quarterNote/4.0), intensity) playNote(67, int(quarterNote), intensity) playNote(65, int(quarterNote), intensity) playNote(67, int(quarterNote/2.0), intensity) playNote(72, int(quarterNote/4.0), intensity) playNote(67, int(quarterNote/4.0), intensity) playNote(67, int(quarterNote), intensity) playNote(65, int(quarterNote), intensity) playNote(64, int(quarterNote/4.0), intensity) playNote(65, int(quarterNote/4.0), intensity) playNote(66, int(quarterNote/4.0), intensity) playNote(67, int(quarterNote/4.0), intensity) playNote(67, int(quarterNote), intensity) playNote(65, int(quarterNote), intensity) playNote(64, int(quarterNote/4.0), intensity) playNote(65, int(quarterNote/4.0), intensity) playNote(66, int(quarterNote/4.0), intensity) playNote(67, int(quarterNote/4.0), intensity) playNote(67, int(quarterNote), intensity) playNote(65, int(quarterNote), intensity) playNote(65, int(quarterNote/32.0), intensity) playNote(64, int(quarterNote/2.0), intensity) playNote(62, int(quarterNote/4.0), intensity) playNote(60, int(quarterNote/4.0), intensity) playNote(64, int(quarterNote/32.0), intensity) playNote(62, int(quarterNote/2.0), intensity) playNote(60, int(quarterNote/4.0), intensity) playNote(59, int(quarterNote/4.0), intensity) playNote(60, int(quarterNote/4.0), intensity) playNote(64, int(quarterNote/4.0), intensity) playNote(60, int(quarterNote/2.0), intensity) playNote(60, int(quarterNote/2.0), intensity) playNote(55, int(quarterNote/4.0), intensity) playNote(58, int(quarterNote/4.0), intensity) playNote(58, int(quarterNote), intensity) playNote(57, int(quarterNote/2.0), intensity) playNote(55, int(quarterNote/4.0), intensity) playNote(53, int(quarterNote/4.0), intensity)

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playNote(52, int(quarterNote/4.0), intensity) playNote(60, int(quarterNote/4.0), intensity) playNote(55, int(quarterNote/4.0), intensity) playNote(58, int(quarterNote/4.0), intensity) playNote(58, int(quarterNote/32.0), intensity) playNote(57, int(quarterNote/2.0), intensity) playNote(55, int(quarterNote/4.0), intensity) playNote(53, int(quarterNote/4.0), intensity) playNote(52, int(quarterNote), intensity) playNote(50, int(quarterNote), intensity) playNote(48, int(quarterNote), intensity) 9.24 Challenging: Take any song you want and play it by using the recorded bassoon notes in the media folder, shifting them up and down in frequency to create the right notes.

Note: The best way to answer this challenge is to make use of the shift function from earlier in the chapter, but to rewrite it to translate to the required frequency. Additionally, one cannot simply call “play” as they will play all at once. A proof of concept is below: def hotCrossBuns(): c4 = makeSound("bassoon-c4.wav") cFreq = 261.63 dFreq = 293.67 eFreq = 329.63 quarterNote = getLength(c4)/4 eQuarter = shift2(c4, cFreq, eFreq, quarterNote) dQuarter = shift2(c4, cFreq, dFreq, quarterNote) target = makeEmptySoundBySeconds(10) targetIndex = 0 #Measure 1 for index in range(0, quarterNote): sourceValue = getSampleValueAt(eQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 for index in range(0, quarterNote): sourceValue = getSampleValueAt(dQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1

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for index in range(0, quarterNote*2): sourceValue = getSampleValueAt(c4,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 #Measure 2 for index in range(0, quarterNote): sourceValue = getSampleValueAt(eQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 for index in range(0, quarterNote): sourceValue = getSampleValueAt(dQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 for index in range(0, quarterNote*2): sourceValue = getSampleValueAt(c4,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 #Measure 3 for index in range(0, quarterNote/2): sourceValue = getSampleValueAt(dQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 for index in range(0, quarterNote/2): sourceValue = getSampleValueAt(dQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 for index in range(0, quarterNote/2): sourceValue = getSampleValueAt(dQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 for index in range(0, quarterNote/2): sourceValue = getSampleValueAt(dQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 for index in range(0, quarterNote/2): sourceValue = getSampleValueAt(eQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 for index in range(0, quarterNote/2): sourceValue = getSampleValueAt(eQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue)

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targetIndex+=1 for index in range(0, quarterNote/2): sourceValue = getSampleValueAt(eQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 for index in range(0, quarterNote/2): sourceValue = getSampleValueAt(eQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 #Measure 4 for index in range(0, quarterNote): sourceValue = getSampleValueAt(eQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 for index in range(0, quarterNote): sourceValue = getSampleValueAt(dQuarter,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 for index in range(0, quarterNote*2): sourceValue = getSampleValueAt(c4,int(index)) setSampleValueAt(target , targetIndex , sourceValue) targetIndex+=1 play(target) return target def shift2(source, startFrequency, goalFrequency, length): target = makeEmptySound(length) sourceIndex = 0 factor = (goalFrequency/startFrequency) for targetIndex in range(0, getLength(target)): sourceValue = getSampleValueAt(source,int(sourceIndex)) setSampleValueAt(target , targetIndex , sourceValue) sourceIndex = sourceIndex + factor if (sourceIndex >= getLength(source)): sourceIndex = sourceIndex - getLength(source) return target

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Chapter 10 10.1 Typically, one does not optimize a program (make it run faster or with less use of memory) until after it is running, well-debugged, and well-tested. (Of course, you still have to test again after each optimizing modification.) Here is an optimization that we could make to the adventure game. Currently, showRoom compares the room variable to each possible room—even if it matched earlier. Python gives us a way of only testing once, by using an elif instead of later if statements. The statement elif means “else if.”

You only test the elif statement if the earlier if was false. You may have as many elif statements as you like after an if. You might use it like this: if (room == ‘‘Porch’’): showPorch() elif (room == ‘‘Kitchen’’): showKitchen() Rewrite the showRoom method more optimally by using elif. def showRoom(room): printNow("===========") if room == "Porch": showPorch() elif room == "Entryway": showEntryway() elif room == "Kitchen": showKitchen() el if room == "LivingRoom": showLR () el if room == "DiningRoom": showDR () 10.2 A function like pickRoom is hard to read with all the nested if statements. It can be made clearer with appropriate use of comments to explain what each section of the code is doing—checking the room, then checking the possible directions in the room. Add comments to pickRoom to make it easier to read. def pickRoom(direction , room): #This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return "Exit" #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room

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#The section below checks each room, then checks the possible directions in the room #"Porch" room direction handling if room == "Porch": if direction == "north": return "Entryway" #"Entryway" room direction handling if room == "Entryway": if direction == "north": return "Kitchen" if direction == "east": return "LivingRoom" if direction == "south": return "Porch" #"Kitchen" room direction handling if room == "Kitchen": if direction == "east": return "DiningRoom" if direction == "south": return "Entryway" #"Livingroom" room direction handling if room == "LivingRoom": if direction == "west": return "Entryway" if direction == "north": return "DiningRoom" #"DiningRoom" room direction handling if room == "DiningRoom": if direction == "west": return "Kitchen" if direction == "south": return "LivingRoom" #This last section handles invalid commands printNow("You can't (or don't want to) go in that direction.") return room 10.3 Add comments to all the methods, to make it easier for someone else to read the function.

Note: By “all” methods, this question refers to all the adventure game methods of Chapter 10 not yet commented. These being: playGame (Program 133), showEntryway, showKitchen, showKitchen, showLR, showDR, and showIntroduction. Comments should explain sections of the code in simple English. An example for playGame is below. def playGame ():

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#The initial location of the player location = "Porch" showIntroduction() #Shows the intro text #Continue to run the game until the exit is reached #Each loop the current room is shown, a direction is requested, #and a new location is determined based on the direction while not (location == "Exit") : showRoom(location) direction = requestString("Which direction?") printNow("You typed: "+direction) location = pickRoom(direction, location) 10.4 Add another global variable for the player, called a hand. Make the hand initially empty. Change the description so that there is a “key” in the Living Room. If the player types the command key while in the Living Room, the key gets put in the hand. Now, if the player has the key when entering the Kitchen, the stairs become accessible, allowing the player to go “west” and up the stairs. You will have to add some rooms to the game to make this work.

Note: The rooms the question refers to are the stairs and some room for the stairs to lead up to. Below are the methods that need to be changed for this question, with the addition of the hand variable at the file level as well. #The variable to track what's in the player's hand hand = "Empty" #This method prints out the description for the current rooms def showRoom(room): printNow("===========") if room =="Porch": showPorch() elif room == "Entryway": showEntryway() elif room =="Kitchen": showKitchen() elif room=="LivingRoom": showLR() elif room=="DiningRoom": showDR() elif room=="Stairs": showStairs() elif room=="MysteryRoom": showMR() #This method prints the description for the Kitchen def showKitchen (): global ghost

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printNow("You are in the kitchen. ") printNow("All the surfaces are covered with pots,") printNow(" pans, food pieces, and pools of blood.") printNow("You think you hear something up the stairs") printNow(" that go up the west side of the room.") printNow("It's a scraping noise, like something being dragged") printNow(" along the floor.") #This section adds a description if the ghost is "in" the room if ghost ==1: printNow("You see the mist you saw earlier.") printNow("But now it's darker, and red.") printNow("The moan increases in pitch and volume") printNow(" so now it sounds more like a yell!") printNow("Then it's gone.") #This sets the ghost to be "in" the Entryway ghost = 0 if hand=="Key": printNow("You notice a hidden, locked door to the west.") printNow("Good thing you found that key.") printNow("You can go to the south or east.") #showLR prints the description of the LivingRoom def showLR(): printNow("You are in a living room.") printNow("There are couches, chairs, and small tables.") printNow("Everything is covered in dust and spider webs.") printNow("You hear a crashing noise in another room.") printNow("You can go north or west.") if not hand=="Key": printNow("There is a key here.") #showStairs prints the description of the Stairs def showStairs(): printNow("You are at the bottom of the stairs.") printNow("The wood of the stairs is old and rotten.") printNow("To your east is the Kitchen.") printNow("You can go up the stairs to the Mystry Room.") #showMR prints the description of the MysteryRoom def showMR(): printNow("What could this room be?") printNow("You can go down to the stairs") #This method actually parses user directions to determine what changes should occur def pickRoom(direction , room): global hand

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#This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return "Exit" #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room #The section below checks each room, then checks the possible directions in the room #"Porch" room direction handling if room == "Porch": if direction == "north": return "Entryway" #"Entryway" room direction handling elif room == "Entryway": if direction == "north": return "Kitchen" elif direction == "east": return "LivingRoom" elif direction == "south": return "Porch" #"Kitchen" room direction handling elif room == "Kitchen": if direction == "east": return "DiningRoom" elif direction == "south": return "Entryway" elif direction=="west" and hand=="Key": return "Stairs" #"Livingroom" room direction handling elif room == "LivingRoom": if direction == "west": return "Entryway" elif direction == "north": return "DiningRoom" elif direction == "key" or direction == "Key": hand = "Key" return "LivingRoom" #"DiningRoom" room direction handling elif room == "DiningRoom": if direction == "west": return "Kitchen" elif direction == "south": return "LivingRoom"

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#"Stairs" room direction handling elif room=="Stairs": if direction =="east": return "Kitchen" elif direction == "up": return "MysteryRoom" elif room == "MysteryRoom": if direction == "down": return "Stairs" #This last section handles invalid commands printNow("You can't (or don't want to) go in that direction.") return room 10.5 Create the ability to go down from the Porch, to explore a secret underground world.

Note: An answer does not need to include any hint in the porch description that the player can go down. #This method just prints out the description for the current rooms def showRoom(room): printNow("===========") if room =="Porch": showPorch() elif room == "Entryway": showEntryway() elif room =="Kitchen": showKitchen() elif room=="LivingRoom": showLR() elif room=="DiningRoom": showDR() elif room=="Stairs": showStairs() elif room=="MysteryRoom": showMR() elif room == "UndergroundWorld": showUW() #This method prints the description for the Porch def showPorch(): printNow("You are on the porch of a frightening looking house.") printNow("The windows are broken. It's a dark and stormy night.") printNow("You can go north into the house. If you dare.") printNow("You can hear something down below.")

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#showUW prints the description of the secret Underground World (UndergroundWorld) def showUW(): printNow("You are in a vast underground cavern.") printNow("You can go up to the Porch.") #This method actually parses user directions to determine what changes should occur def pickRoom(direction , room): global hand #This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return "Exit" #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room #The section below checks each room, then checks the possible directions in the room #"Porch" room direction handling if room == "Porch": if direction == "north": return "Entryway" elif direction == "down": return "UndergroundWorld" #"Entryway" room direction handling elif room == "Entryway": if direction == "north": return "Kitchen" elif direction == "east": return "LivingRoom" elif direction == "south": return "Porch" #"Kitchen" room direction handling elif room == "Kitchen": if direction == "east": return "DiningRoom" elif direction == "south": return "Entryway" elif direction=="west" and hand=="Key": return "Stairs" #"Livingroom" room direction handling elif room == "LivingRoom": if direction == "west": return "Entryway" elif direction == "north":

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return "DiningRoom" elif direction == "key" or direction == "Key": hand = "Key" return "LivingRoom" #"DiningRoom" room direction handling elif room == "DiningRoom": if direction == "west": return "Kitchen" elif direction == "south": return "LivingRoom" #"Stairs" room direction handling elif room=="Stairs": if direction =="east": return "Kitchen" elif direction == "up": return "MysteryRoom" elif room == "MysteryRoom": if direction == "down": return "Stairs" elif room == "UndergroundWorld": if direction == "up": return "Porch" #This last section handles invalid commands printNow("You can't (or don't want to) go in that direction.") return room 10.6 Add additional secret items to have in the player’s hand to allow different rooms to be accessed, such as a lantern to allow access to a tunnel under the Porch.

Note: An answer needs to have at least two items added. In this case the answer adds a lantern as described and a crowbar to access a secret storage area in the kitchen. #This method just prints out the description for the current rooms def showRoom(room): printNow("===========") if room =="Porch": showPorch() elif room == "Entryway": showEntryway() elif room =="Kitchen": showKitchen() elif room=="LivingRoom": showLR() elif room=="DiningRoom": showDR()

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elif room=="Stairs": showStairs() elif room=="MysteryRoom": showMR() elif room == "UndergroundWorld": showUW() elif room == "Tunnel": showTunnel() elif room == "Storage": showStorage() #This method prints the description for the Porch def showPorch(): printNow("You are on the porch of a frightening looking house.") printNow("The windows are broken. It's a dark and stormy night.") printNow("You can go north into the house. If you dare.") printNow("You can hear something down below.") if not hand=="Lantern": printNow("You see a lantern in a corner of the porch") #This method prints the description for the Kitchen def showKitchen (): global ghost printNow("You are in the kitchen. ") printNow("All the surfaces are covered with pots,") printNow(" pans, food pieces, and pools of blood.") printNow("You think you hear something up the stairs") printNow(" that go up the west side of the room.") printNow("It's a scraping noise, like something being dragged") printNow(" along the floor.") #This section adds a description if the ghost is "in" the room if ghost ==1: printNow("You see the mist you saw earlier.") printNow("But now it's darker, and red.") printNow("The moan increases in pitch and volume") printNow(" so now it sounds more like a yell!") printNow("Then it's gone.") #This sets the ghost to be "in" the Entryway ghost = 0 if hand=="Key": printNow("You notice a hidden, locked door to the west.") printNow("Good thing you found that key.") if not hand == "Crowbar": printNow("You spot a crowbar among the pots")

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else: printNow("A chunk of wall to the north seems odd ") printNow(" with the crowbar you may be able to open it.") printNow("You can go to the south or east.") #showUW prints the description of the secret Underground World (UndergroundWorld) def showUW(): printNow("You are in a vast underground world.") if hand == "Lantern": printNow("The lantern reveals a tunnel to the north") printNow("You can go up to the Porch.") #showTunnel prints the description of the tunnel off the underground world def showTunnel(): printNow("You are in a dark, twisting tunnel") printNow("You can go south to the Underground World.") #showStorage prints the description of the storage def showStorage(): printNow("You are in a small storage area.") printNow("You can go south to the Kitchen.") #This method actually parses user directions to determine what changes should occur def pickRoom(direction , room): global hand #This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return "Exit" #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room #The section below checks each room, then checks the possible directions in the room #"Porch" room direction handling if room == "Porch": if direction == "north": return "Entryway" elif direction == "down": return "UndergroundWorld" elif direction == "Lantern" or direction == "lantern": hand = "Lantern" return "Porch" #"Entryway" room direction handling elif room == "Entryway":

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if direction == "north": return "Kitchen" elif direction == "east": return "LivingRoom" elif direction == "south": return "Porch" #"Kitchen" room direction handling elif room == "Kitchen": if direction == "east": return "DiningRoom" elif direction == "south": return "Entryway" elif direction=="west" and hand=="Key": return "Stairs" elif direction=="north" and hand=="Crowbar": return "Storage" elif direction == "Crowbar" or direction == "crowbar": hand = "Crowbar" return "Kitchen" #"Livingroom" room direction handling elif room == "LivingRoom": if direction == "west": return "Entryway" elif direction == "north": return "DiningRoom" elif direction == "key" or direction == "Key": hand = "Key" return "LivingRoom" #"DiningRoom" room direction handling elif room == "DiningRoom": if direction == "west": return "Kitchen" elif direction == "south": return "LivingRoom" #"Stairs" room direction handling elif room=="Stairs": if direction =="east": return "Kitchen" elif direction == "up": return "MysteryRoom" elif room == "MysteryRoom": if direction == "down": return "Stairs" elif room == "UndergroundWorld": if direction == "up": return "Porch"

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if direction =="north" and hand=="Lantern": return "Tunnel" elif room == "Tunnel": if direction =="south": return "UndergroundWorld" elif room == "Storage": if direction =="south": return "Kitchen" #This last section handles invalid commands printNow("You can't (or don't want to) go in that direction.") return room 10.7 Add a “bomb” in the Dining Room. If the player types bomb in the Dining Room, the bomb goes in the hand. If the player types bomb in the upstairs where the Ogre is, the bomb is dropped and the Ogre is blasted to smithereens.

Note: This question assumes that the upstairs room has an ogre in it, so the answer will need to add that. Additionally, as its not possible to get up the stairs without the key and the play can only hold one object at a time, this question requires that a variable be added to check if the stairs have been unlocked. #The variable to track if the stair has been unlocked stairsUnlocked = false #Whether or not ogre is alive or not ogreAlive = true #This method prints the description for the Kitchen def showKitchen (): global ghost global stairsUnlocked printNow("You are in the kitchen. ") printNow("All the surfaces are covered with pots,") printNow(" pans, food pieces, and pools of blood.") printNow("You think you hear something up the stairs") printNow(" that go up the west side of the room.") printNow("It's a scraping noise, like something being dragged") printNow(" along the floor.") #This section adds a description if the ghost is "in" the room if ghost ==1: printNow("You see the mist you saw earlier.") printNow("But now it's darker, and red.") printNow("The moan increases in pitch and volume") printNow(" so now it sounds more like a yell!") printNow("Then it's gone.") #This sets the ghost to be "in" the Entryway ghost = 0

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if hand=="Key" and not stairsUnlocked: printNow("You notice a hidden, locked door to the west.") printNow("Good thing you found that key.") elif stairsUnlocked: printNow("There's a hidden, unlocked door to the west.") if not hand == "Crowbar": printNow("You spot a crowbar among the pots") else: printNow("A chunk of wall to the north seems odd ") printNow(" with the crowbar you may be able to open it.") printNow("You can go to the south or east.") #showLR prints the description of the LivingRoom def showLR(): printNow("You are in a living room.") printNow("There are couches, chairs, and small tables.") printNow("Everything is covered in dust and spider webs.") printNow("You hear a crashing noise in another room.") printNow("You can go north or west.") if not hand=="Key" and not stairsUnlocked: printNow("There is a key here.") #showDR prints the description of the DiningRoom def showDR(): printNow("You are in the dining room.") printNow("There are remains of a meal on the table.") printNow(" You can't tell what it is,") printNow(" and maybe don't want to.") printNow("Was that a thump to the west?") printNow("You can go south or west") if not hand == "Bomb" and ogreAlive: printNow("You spot a bomb on the table.") #showMR prints the description of the MysteryRoom def showMR(): global ogreAlive if not ogreAlive: printNow("Smithereens that used to be an Orge are here.") else: printNow("A fearsome Orge sits at the top of the stairs.") printNow("You can go down to the Stairs.") #This method actually parses user directions to determine what changes should occur def pickRoom(direction , room): global hand

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global stairsUnlocked global ogreAlive #This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return "Exit" #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room #The section below checks each room, then checks the possible directions in the room #"Porch" room direction handling if room == "Porch": if direction == "north": return "Entryway" elif direction == "down": return "UndergroundWorld" elif direction == "Lantern" or direction == "lantern": hand = "Lantern" return "Porch" #"Entryway" room direction handling elif room == "Entryway": if direction == "north": return "Kitchen" elif direction == "east": return "LivingRoom" elif direction == "south": return "Porch" #"Kitchen" room direction handling elif room == "Kitchen": if direction == "east": return "DiningRoom" elif direction == "south": return "Entryway" elif direction=="west" and (hand=="Key" or stairsUnlocked): stairsUnlocked = true return "Stairs" elif direction=="north" and hand=="Crowbar": return "Storage" elif direction == "Crowbar" or direction == "crowbar": hand = "Crowbar" return "Kitchen" #"Livingroom" room direction handling elif room == "LivingRoom":

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if direction == "west": return "Entryway" elif direction == "north": return "DiningRoom" elif direction == "key" or direction == "Key": hand = "Key" return "LivingRoom" #"DiningRoom" room direction handling elif room == "DiningRoom": if direction == "west": return "Kitchen" elif direction == "south": return "LivingRoom" elif direction == "bomb" or direction=="Bomb": hand = "Bomb" return "DiningRoom" #"Stairs" room direction handling elif room=="Stairs": if direction =="east": return "Kitchen" elif direction == "up": return "MysteryRoom" elif room == "MysteryRoom": if direction == "down": return "Stairs" elif direction == "Bomb" or direction=="bomb": printNow("You drop the bomb, blasting the ogre into smithereens.") ogreAlive = false return "MysteryRoom" elif room == "UndergroundWorld": if direction == "up": return "Porch" if direction =="north" and hand=="Lantern": return "Tunnel" elif room == "Tunnel": if direction =="south": return "UndergroundWorld" elif room == "Storage": if direction =="south": return "Kitchen" #This last section handles invalid commands printNow("You can't (or don't want to) go in that direction.") return room

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10.8 Add the ability for the player to lose the game (perhaps die). When the player loses, the game should print what happened, and then the game exits. Perhaps finding the Ogre without the bomb in the player’s hand will make the player lose the game.

Note: The only change necessary for this answer should be to pickRoom. #This method actually parses user directions to determine what changes should occur def pickRoom(direction , room): global hand global stairsUnlocked global ogreAlive #This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return "Exit" #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room #The section below checks each room, then checks the possible directions in the room #"Porch" room direction handling if room == "Porch": if direction == "north": return "Entryway" elif direction == "down": return "UndergroundWorld" elif direction == "Lantern" or direction == "lantern": hand = "Lantern" return "Porch" #"Entryway" room direction handling elif room == "Entryway": if direction == "north": return "Kitchen" elif direction == "east": return "LivingRoom" elif direction == "south": return "Porch" #"Kitchen" room direction handling elif room == "Kitchen": if direction == "east": return "DiningRoom" elif direction == "south": return "Entryway" elif direction=="west" and (hand=="Key" or stairsUnlocked): stairsUnlocked = true

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return "Stairs" elif direction=="north" and hand=="Crowbar": return "Storage" elif direction == "Crowbar" or direction == "crowbar": hand = "Crowbar" return "Kitchen" #"Livingroom" room direction handling elif room == "LivingRoom": if direction == "west": return "Entryway" elif direction == "north": return "DiningRoom" elif direction == "key" or direction == "Key": hand = "Key" return "LivingRoom" #"DiningRoom" room direction handling elif room == "DiningRoom": if direction == "west": return "Kitchen" elif direction == "south": return "LivingRoom" elif direction == "bomb" or direction=="Bomb": hand = "Bomb" return "DiningRoom" #"Stairs" room direction handling elif room=="Stairs": if direction =="east": return "Kitchen" elif direction == "up": if hand=="Bomb": return "MysteryRoom" else: printNow("===========") printNow("You get to the top of the stairs ") printNow(" only to find a hungry Ogre. Without a ") printNow(" weapon to fend him off, he gobbles you up.") printNow("The End.") return "Exit" elif room == "MysteryRoom": if direction == "down": return "Stairs" elif direction == "Bomb" or direction=="bomb": printNow("You drop the bomb, blasting the ogre into smithereens.") ogreAlive = false return "MysteryRoom" elif room == "UndergroundWorld":

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if direction == "up": return "Porch" if direction =="north" and hand=="Lantern": return "Tunnel" elif room == "Tunnel": if direction =="south": return "UndergroundWorld" elif room == "Storage": if direction =="south": return "Kitchen" #This last section handles invalid commands printNow("You can't (or don't want to) go in that direction.") return room 10.9 Add the ability for the player to win the game. When the player wins, the game should print what happened and exit the game. Perhaps finding the secret treasure room under the Porch would make the player win the game.

Note: This question seems to imply the existence of a treasure room, but a new room method does not need to be created to answer it. #showTunnel prints the description of the tunnel off the underground world def showTunnel(): printNow("You are in a dark, twisting tunnel") printNow("You can see a shining gold light to the north") printNow("You can go south to the Underground World.") #This method actually parses user directions to determine what changes should occur def pickRoom(direction , room): global hand global stairsUnlocked global ogreAlive #This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return "Exit" #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room #The section below checks each room, then checks the possible directions in the room #"Porch" room direction handling if room == "Porch": if direction == "north":

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return "Entryway" elif direction == "down": return "UndergroundWorld" elif direction == "Lantern" or direction == "lantern": hand = "Lantern" return "Porch" #"Entryway" room direction handling elif room == "Entryway": if direction == "north": return "Kitchen" elif direction == "east": return "LivingRoom" elif direction == "south": return "Porch" #"Kitchen" room direction handling elif room == "Kitchen": if direction == "east": return "DiningRoom" elif direction == "south": return "Entryway" elif direction=="west" and (hand=="Key" or stairsUnlocked): stairsUnlocked = true return "Stairs" elif direction=="north" and hand=="Crowbar": return "Storage" elif direction == "Crowbar" or direction == "crowbar": hand = "Crowbar" return "Kitchen" #"Livingroom" room direction handling elif room == "LivingRoom": if direction == "west": return "Entryway" elif direction == "north": return "DiningRoom" elif direction == "key" or direction == "Key": hand = "Key" return "LivingRoom" #"DiningRoom" room direction handling elif room == "DiningRoom": if direction == "west": return "Kitchen" elif direction == "south": return "LivingRoom" elif direction == "bomb" or direction=="Bomb": hand = "Bomb" return "DiningRoom"

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#"Stairs" room direction handling elif room=="Stairs": if direction =="east": return "Kitchen" elif direction == "up": if hand=="Bomb": return "MysteryRoom" else: printNow("===========") printNow("You get to the top of the stairs ") printNow(" only to find a hungry Ogre. Without a ") printNow(" weapon to fend him off, he gobbles you up.") printNow("The End.") return "Exit" elif room == "MysteryRoom": if direction == "down": return "Stairs" elif direction == "Bomb" or direction=="bomb": printNow("You drop the bomb, blasting the ogre into smithereens.") ogreAlive = false return "MysteryRoom" elif room == "UndergroundWorld": if direction == "up": return "Porch" if direction =="north" and hand=="Lantern": return "Tunnel" elif room == "Tunnel": if direction =="south": return "UndergroundWorld" if direction == "north": printNow("===========") printNow("You follow the winding tunnel until it ") printNow(" opens out into a cave filled with gold ") printNow(" you grab as much as you can and escape.") printNow("You Win!") return "Exit" elif room == "Storage": if direction =="south": return "Kitchen" #This last section handles invalid commands printNow("You can't (or don't want to) go in that direction.") return room 10.10 Room descriptions do not have to be wholly verbal. Play a relevant sound when the player enters a particular room. Use play, so that game play can continue while the sound

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is playing.

Note: This can be any sound in any room so long as its set up to be accessed after someone calls setMediaPath(). #This method prints the description for the Entryway def showEntryway (): global ghost creak = makeSound("creak.wav") play(creak) printNow("You are in the entry way of the house.") printNow(" There are cobwebs in the corner.") printNow("You feel a sense of dread.") #This section adds a description if the ghost is "in" the room if ghost == 0: printNow("You suddenly feel cold.") printNow("You look up and see a thick mist.") printNow("It seems to be moaning.") printNow("Then it disappears.") #This sets the ghost to be "in" the Kitchen ghost = 1 printNow("There is a passageway to the north and another to the east.") printNow("The porch is behind you to the south.")

10.11 Room descriptions can be visual, as well as textual and auditory. Display a picture relevant to the room when the room is entered. For extra credit, only show a picture once, and if the room is reentered, repaint the picture to bring it back to the front again.

Note: The answer requires at minimum the addition of pictures being shown in each show room function, as below. #This method prints the description for the Porch def showPorch(): pic = makePicture("porch.jpg") show(pic) printNow("You are on the porch of a frightening looking house.") printNow("The windows are broken. It's a dark and stormy night.") printNow("You can go north into the house. If you dare.") printNow("You can hear something down below.") if not hand=="Lantern": printNow("You see a lantern in a corner of the porch") #This method prints the description for the Entryway def showEntryway (): global ghost pic = makePicture("entryway.jpg") show(pic)

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creak = makeSound("creak.wav") play(creak) printNow("You are in the entry way of the house.") printNow(" There are cobwebs in the corner.") printNow("You feel a sense of dread.") #This section adds a description if the ghost is "in" the room if ghost == 0: printNow("You suddenly feel cold.") printNow("You look up and see a thick mist.") printNow("It seems to be moaning.") printNow("Then it disappears.") #This sets the ghost to be "in" the Kitchen ghost = 1 printNow("There is a passageway to the north and another to the east.") printNow("The porch is behind you to the south.") #This method prints the description for the Kitchen def showKitchen (): global ghost global stairsUnlocked pic = makePicture("kitchen.jpg") show(pic) printNow("You are in the kitchen. ") printNow("All the surfaces are covered with pots,") printNow(" pans, food pieces, and pools of blood.") printNow("You think you hear something up the stairs") printNow(" that go up the west side of the room.") printNow("It's a scraping noise, like something being dragged") printNow(" along the floor.") #This section adds a description if the ghost is "in" the room if ghost ==1: printNow("You see the mist you saw earlier.") printNow("But now it's darker, and red.") printNow("The moan increases in pitch and volume") printNow(" so now it sounds more like a yell!") printNow("Then it's gone.") #This sets the ghost to be "in" the Entryway ghost = 0 if hand=="Key" and not stairsUnlocked: printNow("You notice a hidden, locked door to the west.") printNow("Good thing you found that key.") elif stairsUnlocked: printNow("There's a hidden, unlocked door to the west.") if not hand == "Crowbar":

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printNow("You spot a crowbar among the pots") else: printNow("A chunk of wall to the north seems odd ") printNow(" with the crowbar you may be able to open it.") printNow("You can go to the south or east.") #showLR prints the description of the LivingRoom def showLR(): pic = makePicture("livingroom.jpg") show(pic) printNow("You are in a living room.") printNow("There are couches, chairs, and small tables.") printNow("Everything is covered in dust and spider webs.") printNow("You hear a crashing noise in another room.") printNow("You can go north or west.") if not hand=="Key" and not stairsUnlocked: printNow("There is a key here.") #showDR prints the description of the DiningRoom def showDR(): pic = makePicture("diningroom.jpg") show(pic) printNow("You are in the dining room.") printNow("There are remains of a meal on the table.") printNow(" You can't tell what it is,") printNow(" and maybe don't want to.") printNow("Was that a thump to the west?") printNow("You can go south or west") if not hand == "Bomb" and ogreAlive: printNow("You spot a bomb on the table.") #showStairs prints the description of the Stairs def showStairs(): pic = makePicture("stairs.jpg") show(pic) printNow("You are at the bottom of the stairs.") printNow("The wood of the stairs is old and rotten.") printNow("To your east is the Kitchen.") printNow("You can go up the stairs to the Mystry Room.") #showMR prints the description of the MysteryRoom def showMR(): global ogreAlive pic = makePicture("mysteryroom.jpg") show(pic) if not ogreAlive:

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printNow("Smithereens that used to be an Orge are here.") else: printNow("A fearsome Orge sits at the top of the stairs.") printNow("You can go down to the Stairs.") #showUW prints the description of the secret Underground World (UndergroundWorld) def showUW(): pic = makePicture("underground.jpg") show(pic) printNow("You are in a vast underground world.") if hand == "Lantern": printNow("The lantern reveals a tunnel to the north") printNow("You can go up to the Porch.") #showTunnel prints the description of the tunnel off the underground world def showTunnel(): pic = makePicture("tunnel.jpg") show(pic) printNow("You are in a dark, twisting tunnel") printNow("You can see a shining gold light to the north") printNow("You can go south to the Underground World.") #showStorage prints the description of the storage def showStorage(): pic = makePicture("storage.jpg") show(pic) printNow("You are in a small storage area.") printNow("You can go south to the Kitchen.")

Note: For the extra credit, the answer needs to include additional variables to track if a player has entered a room yet or not and the room picture. For example with the porch: porchVisited = false porchPicture = makePicture("porch.jpg") #This method prints the description for the Porch def showPorch(): global porchVisited global porchPicture if porchVisited: repaint(porchPicture) else: show(porchPicture) porchVisited = true printNow("You are on the porch of a frightening looking house.") printNow("The windows are broken. It's a dark and stormy night.")

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printNow("You can go north into the house. If you dare.") printNow("You can hear something down below.") if not hand=="Lantern": printNow("You see a lantern in a corner of the porch") 10.12 A source of possible error in this adventure game is that the names for the rooms appear in several places. If the Dining Room is spelled “DiningRoom” in one place and “DinngRoom” (missing the second “i”) in another place, the game won’t work correctly.

The more rooms you add, and the more places where you have the room names typed, the odds increase that the error will be made.

There are a couple of ways of making this error less likely to occur: • •

Do not name the rooms with strings of characters. Instead, use numbers. It’s easier to type and check “4” than “DiningRoom.”

Use a variable for DiningRoom and use that one variable for checking the location. Then it doesn’t matter if you’re using numbers or strings (and strings are much easier to read and understand). Use one of these techniques to rewrite the adventure game with fewer potential errors.

Note: The first method simply requires replacing each example of the string value for each room with a unique number, as the below: #This method just prints out the description for the current rooms def playGame (): #The initial location of the player location = "1" showIntroduction() #Shows the intro text #Continue to run the game until the exit is reached #Each loop the current room is shown, a direction is requested, #and a new location is determined based on the direction while not (location == "-1") : showRoom(location) direction = requestString("Which direction?") printNow("You typed: "+direction) location = pickRoom(direction, location) def showRoom(room): printNow("===========") if room =="1": showPorch() elif room == "2": showEntryway() elif room =="3": showKitchen() elif room=="4": showLR() elif room=="5":

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showDR() elif room=="6": showStairs() elif room=="7": showMR() elif room == "8": showUW() elif room == "9": showTunnel() elif room == "10": showStorage() etc.

Note: Alternatively, the second method involves the creation of global/file-level variables to store the string values of each room and then to make use of those variables in each place the string value had been used. #Different room string values porch = "Porch" entryway = "Entryway" kitchen = "Kitchen" lr = "LivingRoom" dr = "DiningRoom" stairs = "Stairs" mr = "MysteryRoom" uw = "UndergroundWorld" tunnel = "Tunnel" storage= "Storage" exitLoc = "Exit" def playGame (): #The initial location of the player location = porch showIntroduction() #Shows the intro text #Continue to run the game until the exit is reached #Each loop the current room is shown, a direction is requested, #and a new location is determined based on the direction while not (location == exitLoc) : showRoom(location) direction = requestString("Which direction?") printNow("You typed: "+direction) location = pickRoom(direction, location) #This method just prints out the description for the current rooms def showRoom(room): printNow("===========")

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if room ==porch: showPorch() elif room == entryway: showEntryway() elif room ==kitchen: showKitchen() elif room==lr: showLR() elif room==dr: showDR() elif room==stairs: showStairs() elif room==mr: showMR() elif room == uw: showUW() elif room == tunnel: showTunnel() elif room == storage: showStorage() etc 10.13 Currently, the user must get the case right when typing the directions. Use the lower() method on strings (introduced in Chapter 3) to make the input all in lowercase, so that both “North” and “north” will work as input.

Note: This only needs to be included in the “pickRoom” function #This method actually parses user directions to determine what changes should occur def pickRoom(direction , room): global hand global stairsUnlocked global ogreAlive #Set the direction to the "lower" of the direction direction = direction.lower() #This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return "Exit" #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room #The section below checks each room, then checks the possible directions in the room

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#"Porch" room direction handling if room == porch: if direction == "north": return entryway elif direction == "down": return uw elif direction == "Lantern": hand = "Lantern" return porch #"Entryway" room direction handling elif room == entryway: if direction == "north": return kitchen elif direction == "east": return lr elif direction == "south": return porch #"Kitchen" room direction handling elif room == kitchen: if direction == "east": return dr elif direction == "south": return entryway elif direction=="west" and (hand=="Key" or stairsUnlocked): stairsUnlocked = true return stairs elif direction=="north" and hand=="Crowbar": return storage elif direction == "crowbar": hand = "Crowbar" return kitchen #"Livingroom" room direction handling elif room == lr: if direction == "west": return entryway elif direction == "north": return dr elif direction == "key": hand = "Key" return lr #"DiningRoom" room direction handling elif room == dr: if direction == "west": return kitchen

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elif direction == "south": return lr elif direction == "bomb": hand = "Bomb" return dr #"Stairs" room direction handling elif room==stairs: if direction =="east": return kitchen elif direction == "up": if hand=="Bomb": return mr else: printNow("===========") printNow("You get to the top of the stairs ") printNow(" only to find a hungry Ogre. Without a ") printNow(" weapon to fend him off, he gobbles you up.") printNow("The End.") return exitLoc elif room == mr: if direction == "down": return stairs elif direction=="bomb": printNow("You drop the bomb, blasting the ogre into smithereens.") ogreAlive = false return mr elif room == uw: if direction == "up": return porch if direction =="north" and hand=="Lantern": return tunnel elif room == tunnel: if direction =="south": return uw if direction == "north": printNow("===========") printNow("You follow the winding tunnel until it ") printNow(" opens out into a cave filled with gold ") printNow(" you grab as much as you can and escape.") printNow("You Win!") return exitLoc elif room == storage: if direction =="south": return kitchen #This last section handles invalid commands

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printNow("You can't (or don't want to) go in that direction.") return room 10.14 Let’s start over with a new map. Below is a map of a castle.

Create a new adventure game based on this map. Think Lord of the Rings or maybe Game of Thrones. The player should start on the drawbridge.

Note: This question requires recreation of the entire adventure game in this new setting, meaning new variables and new methods, as seen below. Additionally, each room should have at least some manner of description. #Different room string values drawbridge = "Drawbridge" gate = "Gate" courtyard = "Courtyard" kitchens = "Kitchens" stables = "Stables" hallway = "Hallway" pr = "PrincessRoom" kr = "KingsRoom" wr = "WizardsRoom" skr= "SirKnightsRoom" exitLoc = "Exit" def playGame (): #The initial location of the player location = drawbridge showIntroduction() #Shows the intro text #Continue to run the game until the exit is reached #Each loop the current room is shown, a direction is requested, #and a new location is determined based on the direction while not (location == exitLoc) : showRoom(location) direction = requestString("Which direction?") printNow("You typed: "+direction) location = pickRoom(direction, location) def showIntroduction (): printNow("Welcome to the Dark Castle!") printNow("In each room, you will be told") printNow(" which directions you can go.") printNow("You can move north, south, east, or west") printNow(" by typing that direction.") printNow("Type help to replay this introduction.") printNow("Type quit or exit to end the program.")

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#This method just prints out the description for the current rooms def showRoom(room): printNow("===========") if room ==drawbridge: showDrawbridge() elif room == gate: showGate() elif room ==courtyard: showCourtyard() elif room==kitchens: showKitchens() elif room==stables: showStables() elif room==hallway: showHallway() elif room==pr: showPR() elif room == kr: showKR() elif room == skr: showSKR() elif room == wr: showWR() #This method prints the description for the Drawbridge def showDrawbridge(): printNow("You are on the drawbridge before the Dark Castle.") printNow("Towers like teeth jut into the sky above.") printNow("You can go north to the castle gate. If you dare.") #This method prints the description for the Gate def showGate (): printNow("You are at the castle gate.") printNow("You feel a sense of dread.") printNow("You can see a courtyard to the north") printNow("The drawbridge is behind you to the south.") #This method prints the description for the Courtyard def showCourtyard (): printNow("You are in the courtyard.") printNow("There are tattered flags flying, each one ") printNow(" depicting the wolf's head, the symbol of") printNow(" the dark castle.") printNow("To the west are the castle kitchens.") printNow("To the east are the stables.") printNow("To the south is the castle gate.")

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printNow("To the north is the castle hallway.") #showKitchens prints the description of the Kitchens def showKitchens(): printNow("You are in the kitchens.") printNow("Pots and pans litter the ground. ") printNow("You can hear the skittering of a rat amongst ") printNow(" sacks of grain along the wall. ") printNow("To the east is the courtyard.") #showStables prints the description of the Stables def showStables(): printNow("You are in the stables.") printNow("There's an old gray mare here.") printNow("She's seen better days.") printNow("You can go back west to the courtyard.") #showHallway prints the description of the Hallway def showHallway(): printNow("You are in a long hallway, suits of armor ") printNow(" line the walls. You can't shake the feeling") printNow(" that you're being watched.") printNow("To the north is the Princess room.") printNow("To the west is the King's room.") printNow("To the east is the Sir Knight's room.") printNow("To the south is the courtyard.") #showPR prints the description of the PrincessRoom def showPR(): printNow("You are in the Princess Room.") printNow("The walls are drenched in bright red ") printNow(" the Princess is here, and she is watching you.") printNow("Her gaze is terror.") printNow("You feel that you should leave.") printNow("To the south is the hallway.") #showKR prints the description of the King's Room def showKR(): printNow("You are in the throneroom of the Dark King.") printNow("The Dark King lays broken upon his throne of bones. ") printNow(" He is no longer of the living, yet he is alive.") printNow("To the east is the hallway.") printNow("To the south is the Wizard's Room.") #showSKR prints the description of Sir Knight's Room def showSKR(): printNow("You are in Sir Knight's Room.")

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printNow("A suit of empty armor, and nothing more.") printNow("To the west is the hallway.") #showWR prints the description of the Wizard's Room def showWR(): printNow("You are in the Wizard's Room") printNow("Cauldrons bubble, beakers fizz, and stacks of books") printNow(" create dusty pillars. A crow screeches.") printNow("You can go north to the King's room.") #This method actually parses user directions to determine what changes should occur def pickRoom(direction , room): #Set the direction to the "lower" of the direction direction = direction.lower() #This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return exitLoc #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room #The section below checks each room, then checks the possible directions in the room #"Drawbridge" room direction handling if room == drawbridge: if direction == "north": return gate #"Gate" room direction handling elif room == gate: if direction == "north": return courtyard elif direction == "south": return drawbridge #"Courtyard" room direction handling elif room == courtyard: if direction == "east": return stables elif direction == "south": return gate elif direction=="west": return kitchens elif direction=="north": return hallway #"Kitchens" room direction handling

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elif room == kitchens: if direction == "east": return courtyard #"Stables" room direction handling elif room == stables: if direction == "west": return courtyard #"Hallways" room direction handling elif room==hallway: if direction =="north": return pr elif direction == "east": return skr elif direction == "south": return courtyard elif direction == "west": return kr #Princess Room direction handling elif room == pr: if direction == "south": return hallway #Sir Knight's Room direction handling elif room == skr: if direction == "west": return hallway #King's Room direction handing elif room == kr: if direction =="south": return wr if direction == "east": return hallway #Wizard's Room direction handling elif room == wr: if direction =="north": return kr #This last section handles invalid commands printNow("You can't (or don't want to) go in that direction.") return room 10.15 In the castle game, the player must answer a riddle correctly or provide a password in order to pass through to the Courtyard. Add that to your game.

Note: The answer will need to include a new file-level variable, a change to the showGate function (to prompt the riddle/password) and a change to the pickRoom function (to allow for the riddle/password answer).

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#variable to track if the riddle has been answered riddleAnswered = false #This method prints the description for the Gate def showGate (): printNow("You are at the castle gate.") printNow("You feel a sense of dread.") if not riddleAnswered: printNow("The gate is shut tight. A skull at the gate's top ") printNow(" looks down upon you. In a shrill voice it says: ") printNow(" \"This thing all things devours\"") printNow(" \"Birds, beasts, trees, flowers\"") printNow(" \"Gnaws iron, bits steel\"") printNow(" \"Grings hard stones to meal\"") printNow(" \"Slays king, ruins town, \"") printNow(" \"And beats mountain down.\"") printNow(" \"What am I?\"") else: printNow("You can see a courtyard to the north") printNow("The drawbridge is behind you to the south.") #This method actually parses user directions to determine what changes should occur def pickRoom(direction , room): global riddleAnswered #Set the direction to the "lower" of the direction direction = direction.lower() #This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return exitLoc #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room #The section below checks each room, then checks the possible directions in the room #"Drawbridge" room direction handling if room == drawbridge: if direction == "north": return gate #"Gate" room direction handling elif room == gate: if direction == "north" and riddleAnswered: return courtyard if direction == "time":

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riddleAnswered = true printNow("\"That's it!\" cackles the skull and disappears.") printNow(" The castle gate opens.") return room elif direction == "south": return drawbridge #"Courtyard" room direction handling elif room == courtyard: if direction == "east": return stables elif direction == "south": return gate elif direction=="west": return kitchens elif direction=="north": return hallway #"Kitchens" room direction handling elif room == kitchens: if direction == "east": return courtyard #"Stables" room direction handling elif room == stables: if direction == "west": return courtyard #"Hallways" room direction handling elif room==hallway: if direction =="north": return pr elif direction == "east": return skr elif direction == "south": return courtyard elif direction == "west": return kr #Princess Room direction handling elif room == pr: if direction == "south": return hallway #Sir Knight's Room direction handling elif room == skr: if direction == "west": return hallway #King's Room direction handing elif room == kr: if direction =="south": return wr

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if direction == "east": return hallway #Wizard's Room direction handling elif room == wr: if direction =="north": return kr #This last section handles invalid commands printNow("You can't (or don't want to) go in that direction.") return room 10.16 Games often have nonplayer characters (NPC) which are characters that are not controlled by the player. Add an Evil Wizard to the castle game. When you first play the game, the Evil Wizard is in the Courtyard, and his description says that he is in the Courtyard, but then disappears. Every other time after the first time you enter the Courtyard, the Evil Wizard does not appear in the description. But if you visit the Wizard’s Room, the Evil Wizard can be found there. You defeat him and win the game.

Note: This question requires the addition of a variable to track the appearance of the evil wizard in the courtyard, a change to the showCourtyard function to switch whether or not he appears, and a change in pickRoom or showWR to lead to a win state. #This variable tracks whether or not the evil wizard appears evilWizardAppears = true #This method prints the description for the Courtyard def showCourtyard (): global evilWizardAppears printNow("You are in the courtyard.") printNow("There are tattered flags flying, each one ") printNow(" depicting the wolf's head, the symbol of") printNow(" the dark castle.") if evilWizardAppears: printNow("A robed figure stands in the courtyard's center.") printNow(" \"You cannot take this castle from me!\" ") printNow(" \"My power is absolute!\"") evilWizardAppears = false else: evilWizardAppears = true printNow("To the west are the castle kitchens.") printNow("To the east are the stables.") printNow("To the south is the castle gate.") printNow("To the north is the castle hallway.")

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#This method actually parses user directions to determine what changes should occur def pickRoom(direction , room): global riddleAnswered #Set the direction to the "lower" of the direction direction = direction.lower() #This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return exitLoc #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room #The section below checks each room, then checks the possible directions in the room #"Drawbridge" room direction handling if room == drawbridge: if direction == "north": return gate #"Gate" room direction handling elif room == gate: if direction == "north" and riddleAnswered: return courtyard if direction == "time": riddleAnswered = true printNow("\"That's it!\" cackles the skull and disappears.") printNow(" The castle gate opens.") return room elif direction == "south": return drawbridge #"Courtyard" room direction handling elif room == courtyard: if direction == "east": return stables elif direction == "south": return gate elif direction=="west": return kitchens elif direction=="north": return hallway #"Kitchens" room direction handling elif room == kitchens: if direction == "east": return courtyard #"Stables" room direction handling

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elif room == stables: if direction == "west": return courtyard #"Hallways" room direction handling elif room==hallway: if direction =="north": return pr elif direction == "east": return skr elif direction == "south": return courtyard elif direction == "west": return kr #Princess Room direction handling elif room == pr: if direction == "south": return hallway #Sir Knight's Room direction handling elif room == skr: if direction == "west": return hallway #King's Room direction handing elif room == kr: if direction =="south": printNow("===========") printNow("You enter the room of the Evil Wizard") printNow(" The robed figure appears, chanting words of power.") printNow(" You cut him off with your sword, ridding the") printNow(" castle of his evil magics.") printNow("You Win") return exitLoc if direction == "east": return hallway #Wizard's Room direction handling elif room == wr: if direction =="north": return kr #This last section handles invalid commands printNow("You can't (or don't want to) go in that direction.") return room 10.17 Use the in operator from Chapter 3 to provide some flexibility to the castle game.

Allow the player in the Courtyard to go "north" or "up" to the upper Hallway, or "down" or "south" to return to the Courtyard from the Hallway.

Note: Since this method requires the use of the in keyword, it’s asking that the answer

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make use of strings or collections that combine both direction possibilities. So in the Hallway example, to go north or up would be represented with the string “north up”, as seen below. Alternatively one could make use of a list of both words. #This method actually parses user directions to determine what changes should occur def pickRoom(direction , room): global riddleAnswered #Set the direction to the "lower" of the direction direction = direction.lower() #This code handles the command that quits the game if (direction == "quit") or (direction == "exit"): printNow("Goodbye!") return exitLoc #This section handles the help command which displays the introduction text again if direction == "help": showIntroduction() return room #The section below checks each room, then checks the possible directions in the room #"Drawbridge" room direction handling if room == drawbridge: if direction == "north": return gate #"Gate" room direction handling elif room == gate: if direction == "north" and riddleAnswered: return courtyard if direction == "time": riddleAnswered = true printNow("\"That's it!\" cackles the skull and disappears.") printNow(" The castle gate opens.") return room elif direction == "south": return drawbridge #"Courtyard" room direction handling elif room == courtyard: if direction == "east": return stables elif direction == "south": return gate elif direction=="west": return kitchens elif direction in "north up": return hallway #"Kitchens" room direction handling

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elif room == kitchens: if direction == "east": return courtyard #"Stables" room direction handling elif room == stables: if direction == "west": return courtyard #"Hallways" room direction handling elif room==hallway: if direction =="north": return pr elif direction == "east": return skr elif direction in "south down": return courtyard elif direction == "west": return kr #Princess Room direction handling elif room == pr: if direction == "south": return hallway #Sir Knight's Room direction handling elif room == skr: if direction == "west": return hallway #King's Room direction handing elif room == kr: if direction =="south": printNow("===========") printNow("You enter the room of the Evil Wizard") printNow(" The robed figure appears, chanting words of power.") printNow(" You cut him off with your sword, ridding the") printNow(" castle of his evil magics.") printNow("You Win") return exitLoc if direction == "east": return hallway #Wizard's Room direction handling elif room == wr: if direction =="north": return kr #This last section handles invalid commands printNow("You can't (or don't want to) go in that direction.") return room

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10.18 The function printNow is not the only way to present information to the user during the running of a program. We might also use the function showInformation which takes a string as input, then displays it in a dialog box. Currently, our showRoom subfunctions presume that we will display the room information via printNow. If functions like showPorch returned a string with the description, then the function showRoom could either use printNow to display the room description or showInformation. Rewrite the room showing functions to return a string, then modify showRoom to easily change between printing the room information and showing it in a dialog box.

Note: As stated in the question, each of the show room functions has to be changed to return a string. In particular, in order to ensure that the text is still readable, the altered functions should make use of the new line character “\n”. Additionally, the easiest way to “choose” between two options is to make use of a Boolean to switch between printing and dialog boxes. There’s a number of different potential answers to this question, one approach (as below) is to just write a new function to handle text output, but one could also handle the switching entirely within showRoom. #Determines whether to use printNow or showInformation printOption = false def showText(txt): if printOption: printNow(txt) else: showInformation(txt) #This method just prints out the description for the current rooms def showRoom(room): toPrint = ("===========\n") if room ==drawbridge: toPrint= toPrint+showDrawbridge() elif room == gate: toPrint= toPrint+showGate() elif room ==courtyard: toPrint= toPrint+showCourtyard() elif room==kitchens: toPrint= toPrint+showKitchens() elif room==stables: toPrint= toPrint+showStables() elif room==hallway: toPrint= toPrint+showHallway() elif room==pr: toPrint= toPrint+showPR() elif room == kr: toPrint= toPrint+showKR() elif room == skr: toPrint= toPrint+showSKR()

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elif room == wr: toPrint= toPrint+showWR() return toPrint #This method prints the description for the Drawbridge def showDrawbridge(): toReturn = "" toReturn = toReturn +("You are on the drawbridge before the Dark Castle.\n") toReturn = toReturn +("Towers like teeth jut into the sky above.\n") toReturn = toReturn + ("You can go north to the castle gate. If you dare.\n") return toReturn #This method prints the description for the Gate def showGate (): toReturn = "" toReturn = toReturn +("You are at the castle gate.\n") toReturn = toReturn +("You feel a sense of dread.\n") if not riddleAnswered: toReturn = toReturn +("The gate is shut tight. A skull at the gate's top \n") toReturn = toReturn +(" looks down upon you. In a shrill voice it says: \n") toReturn = toReturn +(" \"This thing all things devours\"\n") toReturn = toReturn +(" \"Birds, beasts, trees, flowers\"\n") toReturn = toReturn +(" \"Gnaws iron, bits steel\"\n") toReturn = toReturn +(" \"Grings hard stones to meal\"\n") toReturn = toReturn +(" \"Slays king, ruins town, \"\n") toReturn = toReturn +(" \"And beats mountain down.\"\n") toReturn = toReturn +(" \"What am I?\"") else: toReturn = toReturn +("You can see a courtyard to the north.\n") toReturn = toReturn +("The drawbridge is behind you to the south.\n") return toReturn #This method prints the description for the Courtyard def showCourtyard (): global evilWizardAppears toReturn="" toReturn = toReturn +("You are in the courtyard.\n") toReturn = toReturn +("There are tattered flags flying, each one \n") toReturn = toReturn +(" depicting the wolf's head, the symbol of\n") toReturn = toReturn +(" the dark castle.\n") if evilWizardAppears: toReturn = toReturn +("A robed figure stands in the courtyard's center.\n") toReturn = toReturn +(" \"You cannot take this castle from me!\" \n") toReturn = toReturn +(" \"My power is absolute!\"\n")

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evilWizardAppears = false else: evilWizardAppears = true toReturn = toReturn +("To the west are the castle kitchens.\n") toReturn = toReturn +("To the east are the stables.\n") toReturn = toReturn +("To the south is the castle gate.\n") toReturn = toReturn +("To the north is the castle hallway.\n") return toReturn etc.

10.19 Consider this program: def testMe(p,q,r): if q > 50: print r value = 10 for i in range(1,p): print "Hello" value = value - 1 print value print r If we execute testMe(5,51,"Hello back to you!"), what will print?

Hello back to you!

Hello Hello Hello Hello 6 Hello back to you!

10.20 def newFunction(a, b, c): print a list1 = range(1,5) value = 0 for x in list1: print b value = value +1 print c print value If you call the preceding function by typing newFunction("I", "you", "walrus"), what will the computer print?

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I you you you you walrus 4

Chapter 11 11.1 Create a string variable that contains the sentence “Don’t do that!” in it. Create a string variable that contains double quotes in it. Create a string variable that has a tab in it. Create a string variable that has a filename in it with backslashes. var = "Don't do that!" var2 = '"What do you mean?" asked Harry' (Source: Chapter 3, Page 45) or var2 = "\"What do you mean?\" asked Harry" (Source: var3 = "This sentence sure is \t drawn out" (Source: Chapter 3, Page 66) var4 = r"C:\ip-book\mediasources\barbara.jpg" (Source: Chapter 3, Page 67) 11.2 Write a function that prints every other letter in a string.

Note: If the answer assumes that the string only contains letters, an answer might look like the below. def everyOther(source): for index in range(0, len(source)): if index%2==0: print source[index] (Source for len: Chapter 3, Page 46) Note: Otherwise, the answer needs to check if a character is a letter before printing it. def everyOther2(source): letterIndex= 0 for index in range(0, len(source)): if source[index].isalpha(): if letterIndex%2==0: print source[index] letterIndex=letterIndex+1 (Source for isalpha: Chapter 11, Page 311) 11.3 Write a function that takes a string and prints out the letters in the string in reverse order.

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Note: Similar to the previous question, an answer can assume that the string passed in is a letter, but a more accurate answer is one that checks if each index of a string is a letter as the below does. def reverseLetters(source): for index in range(len(source)-1, -1, -1): if source[index].isalpha(): print source[index] 11.4 Write a function that finds and removes the second occurrence of a given string in a passed string.

Note: An answer could make use of a variety of techniques (such as looping through the string in some way), but the easiest way is to make use of the find method (Chapter 11, Page 330) and making a substring. def secondIndex(passedString, givenString): index = passedString.find(givenString) return passedString.find(givenString, index+1) 11.5 Write a function to uppercase every other word in a passed sentence. So given “The dog ran a long way,” it would output “The DOG ran A long WAY.” def upperCaseOthers(source): parts = source.split(" ") index = 0 newString = "" for p in parts: if index%2==1: p = p.upper() index = index+1 newString =newString+ p+" " lastIndex = len(newString)-1-1 return newString[0:lastIndex] 11.6 Write a function that takes a passed sentence and an index and returns the sentence with the word at the index uppercased. For example, if the function takes in a sentence “I love the color red” and the index 4 it returns “I love the color RED.” def upperWordAtIndex(source, indexUpper): parts = source.split(" ") newString = "" index=0 for p in parts: if index==indexUpper: p = p.upper() index = index+1

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newString =newString+ p+" " lastIndex = len(newString)-1-1 return newString[0:lastIndex] 11.7 Change the function findPopulation to change the input and the comparison word both to lowercase. Now, it will match even if we executed findPopulation("CALIFORNIA").

Note: As the question suggests, this just requires two changes to findPopulation. def findPopulation(state): file = open(getMediaPath("state-populations.csv"),"rt") lines = file.readlines() file.close() for line in lines: parts = line.split(",") if parts[4].lower() == state.lower(): return int(parts[5]) return -1 11.8 Write a function that takes a sentence as input and returns it scrambled (the order of the words mixed up in some way). For example, if it is passed “Does anything rhyme with orange?” it might return “Orange with does anything rhyme?”.

Note: With the example the question gives, its implied that the answer needs to include capitalizing the first letter of the first word, lower-caseing the original first word, and ensuring that the punctuation mark at the end stays consistent. import random def scramble(source): mark = source[-1] source = source[0:len(source)-1-1] parts = source.split(" ") newString = "" while len(parts)>0: p = random.choice(parts) parts.remove(p) newString = newString+p.lower()+" " lastIndex = len(newString)-1 newString = newString[0:lastIndex] +mark newString= newString[0].upper() + newString[1:] return newString 11.9 Write a function that can find the zip code for a person from a delimited string for an address. For example, it might read a string that has in it “name:line1:line2: city:state:zipCode” and return the zip code.

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Note: In the answer, it’s acceptable to assume that the delimiting string will be passed in to the function as well. Additionally, the answer can make the assumption that the zip code will always be the last section. def findZipcode(source, delimit): parts = source.split(delimit) return parts[len(parts)-1] 11.10 Modify the changeLittle function to use readLines instead of read.

Note: The question refers to the “readlines” method. def changeLittle(filename ,newString): # Get the original file contents programFile="littlePicture.py" file = open(getMediaPath(programFile),"rt") lines = file.readlines() file.close() # Now, find and change the line for index in range(0, len(lines)): if "addText" in lines[index]: #First double quote firstQuote = lines[index].find('"') #Double quote after firstQuote endQuote = lines[index].find('"',firstQuote+1) newLine = lines[index][:firstQuote+1]+ newString +lines[index][endQuote:] lines[index] = newLine # Make our new file newFile = open(getMediaPath(filename),"wt") for line in lines: newFile.write(line) newFile.close() 11.11 Modify the changeLittle function to use readLine instead of read.

Note: The question refers to the “readline” method. def changeLittle2(filename ,newString): # Get the original file contents programFile="littlePicture.py" file = open(getMediaPath(programFile),"rt") newFile = open(getMediaPath(filename),"wt") line = file.readline() while line <> '': if "addText" in line: #First double quote

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firstQuote = line.find('"') #Double quote after firstQuote endQuote = line.find('"',firstQuote+1) newLine = line[:firstQuote+1]+ newString +line[endQuote:] newFile.write(newLine) else: newFile.write(line) line = file.readline() file.close() newFile.close() 11.12 Create a secret message by encoding each character of a string into a number using ord. For each character in the message, print the rod of that character.

Note: The word “rod” is a typo, it should be “ord” def secretMessage(source): for s in source: print (ord(s)) 11.13 Create a function that reverses the items in a list.

Note: Creating a new function is unnecessary as there is a built in reverse method for lists, but one could make a function that calls this one. def reverse(list): return list.reverse() (Source: Chapter 11, Page 315) 11.14 Create a function that replaces a passed string in a list of strings with a new string. def replaceString(list, passedString, newString): for index in range(0, len(list)): if list[index] == passedString: list[index] = newString return list 11.15 Are the numbers returned from the random.random() function really random? How are they generated? You will have to look up some information on random numbers on the Internet to answer this question.

(Sources: https://docs.python.org/2/library/random.html and http://www3.nd.edu/~mcbg/tutorials/2006/tutorial_files/randomNum/howItworks.html)

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No they are not “really” random. The numbers are generated by a random number generator known as the Mersenne Twister and are therefore deterministic since they are generated via an algorithm.

11.16 Write short essay responses to these questions: (a) Give me one example of a task for which you would not write a program and give me another example of a task for which you would write a program.

Note: The important things for an answer to include are examples based on things that are difficult for programs and things that are easy. For example: programs can do simple tasks, programs can repeat tasks exactly, and programs can create interactive experiences.

That means that good examples to use programs for would be for a program to search through a lot of text, to alter a sound file, or to serve as an adventure game. It is much harder for programs to complete tasks that cannot be described exactly, to engage with non-digital materials, or to handle extremely specific, non-generalizable tasks. Activities that would not make good programs then would be things like filling out physical forms, writing a short story, or answering questions for an intro to programming class. (b) What’s the difference between an array, a matrix, and a tree? Give an example where we have used each to represent some data of interest to us.

The primary difference between all three is that they are different ways of storing data; they are different data structures. The difference between an array and a matrix is that an array is a single sequence of elements of the same type, while a matrix is a twodimensional array. A tree is different from an array or matrix as it is a hierarchical organization of information rather than a sequence. We have used arrays to represent strings, matrices to represent pictures, and trees to represent file structure.

(Source for array and matrix: Chapter 4, Page 75. Source for tree: Chapter 11, Page 318) (c) What is dot notation and when do you use it?

Dot notation is calling a method by including a period between an object and the method.

For example “foo.bar()” where foo is the object and bar is the method. It is used in calling an object’s methods.

(Source: Chapter 11, Page 313-314) (d) Why is red a bad color to use for chromakey?

Red is a bad color for chromakey as many individuals have significant red pigmentation in their skin.

(Source: Chapter 5, Page 133) (e) What’s the difference between a function and a method?

Methods are like functions except that they’re not globally accessible, they’re linked to

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specific element types.

(Source: Chapter 11, Page 313) (f) Why is a tree a better representation than an array for files on a disk? Why do you have many directories on your disk, and not just one gigantic one?

A tree is a better representation than an array for files on a disk due to it being much better in terms of organization and finding desired files. If there was just one gigantic directory then a user would have to search through all of their files to find a single one. (g) What are some advantages that vector-based graphics have over bitmap graphical representations (like JPEG, BMP, GIF)?

Vector-based graphics can be scaled to different sizes without loss of quality, and they can also take up much less memory then a similar high-quality image.

(Source: Chapter 11, Page 328) 11.17 Extend the form-letter recipe to take an input of a pet’s name and type, and reference the pet in the form letter."Your pet "+petType+","+petName+" will love our offer!" might generate "Your pet poodle, Fifi, will love our offer!".

Note: The answer just needs to include one extra line with the suggested changes. def formLetter(gender,lastName,city,eyeColor, petType, petName): file = open("formLetter.txt","wt") file.write("Dear ") if gender=="F": file.write("Ms. "+lastName+":\n") if gender=="M": file.write("Mr. "+lastName+":\n") file.write("I am writing to remind you of the offer ") file.write("that we sent to you last week. Everyone in ") file.write(city+" knows what an exceptional offer this is!") file.write("(Especially those with lovely eyes of"+eyeColor+"!)") file.write("Your pet "+petType+", "+petName+" will love our offer!") file.write("We hope to hear from you soon.\n") file.write("Sincerely ,\n") file.write("I.M. Acrook , Attorney at Law") file.close() 11.18 Imagine that you have a list of the genders (as single characters) of all the students in your class, in order of their last name. The list will look something like “MFFMMMFFMFMMFFFM” where M is male and F is female. Write a function (below) percentageGenders(string) to accept a string that represents the genders. You are to count all of the M’s and F’s in the string and print out the ratio (as a decimal) of the each gender. For example, if the input string were “MFFF,” then the function should print something like, “There are 0.25 males, 0.75 females.” (Hint: Better multiply something

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by 1.0 to make sure that you get floats not integers.) def percentageGenders(string): mCount = string.count("M") fCount = string.count("F") total = 1.0*(mCount+fCount) mPercentage = (mCount/total) fPercentage = (fCount/total) print("There are "+String(mPercentage)+" males, "+String(fPercentage)+ " females.")

11.19 You worked late into the night on an assignment and didn’t realize that you wrote a huge section of your term paper with your fingers on the wrong home keys. Where you meant to type: “This is an unruly mob.” You actually typed: “Ty8s 8s ah 7hr7o6 j9b.” Basically you swapped: 6 for Y, 7 for U, 8 for I, 9 for O, 0 for P, U for J, I for K, O for L, H for N, and J for M. (Those were the only keystrokes you got wrong—you caught yourself before you got much further.) You also never touched the shift key, so it’s only lowercase letters that you care about. Knowing Python as you do, you decide to write a quick program to fix your text. Write a function fixItUp that takes a string as input and returns a string with the characters put the way that they ought to have been.

Note: The easiest way to accomplish this answer is to make use of the “replace” method.

However, an answer needs to be aware of the order that the replaces occur in. For example, if an answer swaps out I and 8 and then K and I the end result would be some letters that should be I’s becoming K’s. One way to avoid this is to reverse the list of swapped characters and replace in that order, as below. Additionally, the question does not mention it, but in the example it shows that H also got swapped for Y. def replaceCharacters(string): newString = string.replace("j", "m") newString = newString.replace("h", "n") newString = newString.replace("y", "h") newString = newString.replace("o", "l") newString = newString.replace("i", "k") newString = newString.replace("u", "j") newString = newString.replace("0", "p") newString = newString.replace("9", "o") newString = newString.replace("8", "i") newString = newString.replace("7", "u") newString = newString.replace("6", "y") return newString 11.20 Write a function doGraphics that will take a list as input. The function doGraphics will start by creating a canvas from the 640x480.jpg file in the mediasources folder. You will draw on the canvas according to the commands in the input list. Each element of the list will be a string. There will be two kinds of strings in the list: • “b 200 120” means to draw a black dot at x position 200 and y position 120–(200,120).

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The numbers, of course, will change, but the command will always be a “b.” You can assume that the input numbers will always have three digits.

• “l 000 010 100 200” means to draw a line from position (0,10) to position (100,200).

So an input list might look like: ["b 100 200","b 101 200","b 102 200","l 102 200 102 300"] (but have any number of elements).

Note: The important thing here is to iterate through the list’s items and handle each case with the “split” method. def doGraphics (list): canvas = makePicture("640x480.jpg") for item in list: if item[0]=="b": parts = item.split(" ") px = getPixel(canvas, int(parts[1]), int(parts[2])) setColor(px, makeColor(0,0,0)) elif item[0]=="l": parts = item.split(" ") x1 = int(parts[1]) y1 = int(parts[2]) x2 = int(parts[3]) y2 = int(parts[4]) addLine(canvas, x1, y1, x2, y2) return canvas 11.21 Write a function findLargestState that figures out which state has the largest population and returns that.

Note: This answer requires searching through each of the states and checking if its population is greater than the current maximum. Additionally, its necessary to in some way skip the first line, as otherwise parsing a string as an int will lead to an error, and the second line as it’ll get the entire population of the united states. def findLargestState (): file = open(getMediaPath("state-populations.csv"),"rt") lines = file.readlines() file.close() maxState = "None" maxPopulation = 0 for index in range(2, len(lines)): parts = lines[index].split(",") if parts[5].isdigit(): thisPopulation = int(parts[5]) if thisPopulation>maxPopulation:

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maxPopulation = thisPopulation maxState = parts[4] return maxState 11.22 Write a function findSmallestState that figures out which state has the smallest population and returns that.

Note: this is just a reversal of the last method, without a need to pass over the first index. def findSmallestState (): file = open(getMediaPath("state-populations.csv"),"rt") lines = file.readlines() file.close() minState = "None" minPopulation = 0 for index in range(2, len(lines)): parts = lines[index].split(",") if parts[5].isdigit(): thisPopulation = int(parts[5]) if minPopulation == 0 or thisPopulation<minPopulation: minPopulation = thisPopulation minState = parts[4] return minState 11.23 In the media folder, there is another piece of census data that includes city information, state-city-populations.csv. The first few lines of this file look like this: SUMLEV,STATE,COUNTY,PLACE,COUSUB,CONCIT,FUNCSTAT,NAME,STNAME, CENSUS2010POP,ESTIMATESBASE2010,POPESTIMATE2010,POPESTIMATE2011, POPESTIMATE2012,POPESTIMATE2013 040,01,000,00000,00000,00000,A,Alabama,Alabama,4779736,4779758,4785570, 4801627,4817528,4833722 162,01,000,00124,00000,00000,A,Abbeville city,Alabama,2688,2688,2683,2690,2658,2651 162,01,000,00460,00000,00000,A,Adamsville city,Alabama,4522,4522,4519,4496,4474,4448 1

Write the below functions in two ways: One with split and another with the csv module.

• Write the findCityPopulation function that returns the population in 2013 (last field) of an input city. split def findCityPopulation (cityName): file = open(getMediaPath("state-city-populations.csv"),"rt") lines = file.readlines()

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file.close() for index in range(0, len(lines)): parts = lines[index].split(",") if parts[7] ==cityName: return int(parts[14]) return -1 csv module from csv import * def findCityPopulation (cityName): file = open(getMediaPath("state-city-populations.csv"),"rb") csvfile = reader(file) for row in csvfile: if row[7] ==cityName: return int(row[14]) return -1 • Write a function findLargestCityInState and findSmallestCityInState to find the city with the largest and the smallest population (respectively) within a given state.

Note: The findLargestCityInState functions are made more difficult as a row expressing the population of the state begins each section. Therefore, without checking for this an answer will likely find that the largest city in Alabama is Alabama. However it’s easy enough to avoid, as each state section has a first row value of 040. Additionally, since the list also contains towns and counties, to avoid getting one of those, its necessary to check that the potential city has the word “city” in it. split def findLargestCityInState (state): file = open(getMediaPath("state-city-populations.csv"),"rt") lines = file.readlines() file.close() maxState = "None" maxPopulation = 0 for index in range(0, len(lines)): parts = lines[index].split(",") if parts[8] ==state and not parts[0]=="040": thisPopulation = int(parts[14]) if thisPopulation>maxPopulation and "city" in parts[7]: maxPopulation = thisPopulation maxState = parts[7] return maxState def findSmallestCityInState (state):

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file = open(getMediaPath("state-city-populations.csv"),"rt") lines = file.readlines() file.close() minState = "None" minPopulation = 0 for index in range(0, len(lines)): parts = lines[index].split(",") if parts[8] ==state and not parts[0]=="040": thisPopulation = int(parts[14]) if (minPopulation==0 or thisPopulation<minPopulation) and "city" in parts[7]: minPopulation = thisPopulation minState = parts[7] return minState csv module from csv import * def findLargestCityInState (state): file = open(getMediaPath("state-city-populations.csv"),"rb") csvfile = reader(file) maxState = "None" maxPopulation = 0 for row in csvfile: if row[8] == state and not row[0]=="040" and row[14].isdigit(): thisPopulation = int(row[14]) if thisPopulation>maxPopulation and "city" in row[7]: maxPopulation = thisPopulation maxState = row[7] return maxState def findSmallestCityInState (state): file = open(getMediaPath("state-city-populations.csv"),"rb") csvfile = reader(file) minState = "None" minPopulation = 0 for row in csvfile: if row[8] == state and not row[0]=="040" and row[14].isdigit(): thisPopulation = int(row[14]) if (minPopulation==0 or thisPopulation<minPopulation) and "city" in row[7]: minPopulation = thisPopulation minState = row[7] return minState • Use both your state and city functions to answer some questions. Find the state with the largest population, and the state with the smallest population. Is the smallest city in the largest state larger or smaller than the smallest city in the smallest state? Is the largest city

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in the largest state larger or smaller than the largest city in the smallest state?

Largest State Population: California Smallest State Population: Wyoming Smallest City in California: Vernon city Largest City in Wyoming: Cheyenne city Is Vernon city (1955) larger or smaller than Cheyenne city (62448): Much smaller Largest City in California: Los Angeles city Is Los Angeles city (3884307) largeror smaller than Cheyenne city (62448): Much Larger

Chapter 12 12.1 Go to a page with a lot of text in it, like http://www.cnn.com and use your browser’s menus to Save the file as something like myPage.html. Edit the file using JES or even an editor like Windows Notepad. Find some text in the page that you can see when you view the page, like a headline or article text. Change it! Instead of “protesters” rioting, make it “College students” or even “kindergarteners.” Now Open that file in your browser.

You’ve just rewritten the news!

Note: A site like cnn’s may prove challenging in this question as it makes use of mostly javascript, not html for the majority of its site’s functionality. Its much easier to accomplish this task with a site from earlier in the Internet’s history, such as this one: http://www2.warnerbros.com/spacejam/movie/jam.htm Additionally, many browsers like Google Chrome cache web pages, such that changes made to them do not appear. Running such browsers in “incognito” mode or the equivalent can serve as a work around.

12.2 Create a function that visits a news page (maybe for your college) and pulls out all the headers by Web scraping. Put them all in a text file.

Note: Headers in html can have a variety of different notations, as seen here http://www.w3schools.com/tags/tag_hn.asp, the simplest way (as seen below) to answer this question is to save any line that contains one of those tags. A more complicated approach would be to parse each line and to find all the content between the start and end tag in order to only save that text. import urllib def saveHeaders (filename): connect = urllib.urlopen("http://www.news.gatech.edu/") news = connect.read() connect.close() lines = news.split("\n") file = open(filename, "wt")

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for line in lines: if "h1" in line or "h2" in line or "h3" in line or "h4" in line or "h5" in line or "h6" in line: file.write(line+"\n") file.close()

12.3 Create a function that pulls a sound from a URL using urllib and creates a sound clip saved on your local machine. import urllib def saveSound (filename): str ="https://ia902706.us.archive.org/20/items/WilhelmScreamSample/WilhelmScream.wav" connect = urllib.urlopen(str) sound = connect.read() connect.close() file = open(filename, "wb") file.write(sound) file.close()

12.4 Create a function that pulls a picture from a URL and creates a thumbnail saved on your local machine.

Note: Since this question specifies that the picture should be saved as a “thumbnail” a full answer to this question should include some resizing of the image down to a thumbnail size (saveThumbnail2). However, if the picture pulled from a URL was a thumbnail originally, it could be argued that just saving the image without resizing would be sufficient (saveThumbnail1). import urllib def saveThumbnail1 (filename): str = "http://png-1.findicons.com/files/icons/85/kids/128/thumbnail.png" connect = urllib.urlopen(str) image = connect.read() connect.close() file = open(filename, "wb") file.write(image) file.close() import urllib def saveThumbnail2 (filename): str = "http://obeythekitty.com/wp-content/uploads/2015/01/lolcat_flying_cat.jpg" connect = urllib.urlopen(str)

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image = connect.read() connect.close() file = open(filename, "wb") file.write(image) file.close() #Make Thumbnail img = makePicture(filename) width = getWidth(img) height = getHeight(img) img2 = makeEmptyPicture(width/2,height/2) sourceX = 0 for targetX in range(0, width/2): sourceY = 0 for targetY in range(0, height/2): color = getColor(getPixel(img,sourceX,sourceY)) setColor(getPixel(img2 ,targetX ,targetY), color) sourceY = sourceY + 2 sourceX = sourceX + 2 writePictureTo(img2, filename) 12.5 Match the letter of the definition next to the appropriate phrase below. (Yes, you will have one unused definition.)

A.) Domain Name Server D.) Web Server E.) HTTP G.) HTML F.) Client I.) IP Address B.) FTP C.) URL (a) A computer that matches names like www.cnn.com to their addresses on the Internet.

Domain Name Server (Source: Chapter 12, Page 338) (b) A protocol used to move files between computers (e.g., from your personal computer to a larger computer that acts as a Web server).

FTP (Source: Chapter 12, Page 339)

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(c) A string that explains how (what protocol) and on what machine (domain name) and where on the machine (path) a particular file can be found on the Internet.

URL (Source: Chapter 12, Page 339) (d) A computer that offers files through HTTP. Web Server (Source: Chapter 12, Page 339-340) (e) The protocol on which most of the Web is built, a very simple form aimed at rapid transmission of small bits of information.

HTTP (Source: Chapter 12, Page 339) (f) What a browser (like Internet Explorer) is when contacting a server like google.com.

Client (Source: Chapter 12, Page 339-340) (g) The tags that go into Web pages to identify parts of the page and how they should be formatted.

HTML (Source: Chapter 12, Page 339-340) (h) A protocol used for transmitting electronic mail between computers.

Unused! (i) The numeric identifier of a computer on the Internet—four numbers between 0 and 255, like 120.32.189.12.

IP Adress (Source: Chapter 12, Page 338) 12.6 For each of the following, see if you can figure out the representation in terms of bits and bytes. (a) Internet addresses are four numbers, each between 0 and 255. How many bits are in an Internet address?

Since it takes 8 bits to represent 256 numbers, it’ll require four sections of eight bits, meaning (b) In the ancient programming language Basic, lines can be numbered, each one between 0 and 65,535. How many bits are needed to represent a line number?

16, 216=65,536 (c) Each pixel’s color has three components, red, green, and blue, each of which can be

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between 0 and 255. How many bits are needed to represent a pixel’s color?

24 bits, as 8 bits can represent one value between 0 and 255. (d) A string in some systems can only be up to 1,024 characters. How many bits are needed to represent the length of a string?

10 bits, 210=1,024 12.7 What is a domain name server? What does it do?

A domain name server maps names of websites like “www.cnn.com” and maps them to IP Address values like “157.166.226.26”. This mapping can also change, meaning if the server for a company needs to change the name of the website can stay the same.

(Source: Chapter 12, Page 338) 12.8 Investigate how you would buy a domain name (like “mycooldomainname.org”) and register it so that other users could find it. How long does it take your new domain name to be recognized across the Internet?

You can buy a domain name from a variety of different services such as (https://www.namecheap.com/). It typically takes between 24 and 48 hours for the web to fully recognize a new domain name, via a process called “propagation”. (Source: http://www.inmotionhosting.com/support/domain-names/dns-nameserverchanges/domain-names-dns-changes) 12.9 Why does it take any time at all for domain names to be accessible across the Internet?

Networks keep a cache of domain names, and it takes time for this cache to be updated, based on physical location. (Source: http://www.inmotionhosting.com/support/domainnames/dns-nameserver-changes/domain-names-dns-changes) 12.10 What are FTP, SMTP, and HTTP? What are they each used for?

FTP stands for file transfer protocol, which allows individuals to transfer files between computers. SMTP stands for simple mail transfer protocol, which allows for electronic mail (e-mail) transmission (Source: http://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol). HTTP stands for hypertext transfer protocol, which is the protocol used to transfer resources across the Web. 12.11 What is HyperText? Who invented it?

HyperText is “nonlinear” text, text that links to other text. The term was coined by Ted Nelson, but the basic idea of HyperText dates back to Vennevar Bush.

(Source:

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12.12 What is the difference between a client and a server?

A server actually holds resources, while a client is a local piece of software that accesses the server and translates it for the user. (Source: Chapter 12, Page 339) 12.13 How does knowing how to manipulate text help you in gathering and creating information on the Internet?

Because the internet is based on text, specifically using HTML (HyperText Markup Language). (Source: Chapter 12, Page 339) 12.14 What is a Denial of Service Attack? Could you write a program to generate one?

A denial of service attack involves an individual or group attempting to interrupt or suspend services of a host connected to the Internet. The most typical form involves flooding a machine or server with requests such that it can’t deal with legitamite traffic.

One could write a program or series of programs to repeatedly ping a website, but its unlikely one could do it with a single machine. It is also intensely illegal.

(Source: http://en.wikipedia.org/wiki/Denial-of-service_attack) 12.15 What is an ISP? Can you give an example of one?

An ISP is an Internet Service Provider. Comcast is a prominent example of an ISP. (Source: Chapter 12, Page 339) 12.16 The Guardian’s Web site includes CSV data on how often the groundhog correctly predicts Spring on Groundhog Day. Write a program to grab that CSV file and add up the number of corrects and the number of incorrect predictions. Is the groundhog more accurate than chance (50%)?

Note: This CSV file is no longer available online, and this question cannot be completed.

12.17 Is it possible to hide a color picture in another color picture? Why or why not?

Yes, its possible to hide a color picture in another color picture, just not with the technique used in section 12.5 of Chapter 12. For example, one could hide an image in something like a Jackson Pollock-esque image by transforming the position of pixels based on their index in the original image.

12.18 If you erase lower two bits in the red value, you can clear space for hiding values 0–4. for p in getPixels(picture): # Clear out the red 2xLSB r = getRed(p) setRed(p,r-(r%4))

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If you erase the lower two bits from red, green, and blue, you can save six bits. Six bits can encode 64 values. That’s enough to encode all 27 letters, both upper and lower case. (a) Write a function to input a picture and a string. Save each character in the string in a pixel of the picture, by saving it across the least significant two bits in each of red, green, and blue. Can you tell the difference between the original picture and the picture with the encoded text message?

No, it’s highly unlikely someone could tell a difference between the original and the modified picture.

Note: The below method special cases for the space character, as otherwise messages cannot include spaces, this is possible to do as six bits allows for additional space beyond the 54 needed for upper and lower case letters. def encodeMessage(picture, message): #Go through all pixels and erase the lower two bits for p in getPixels(picture): # Clear out the red 2xLSB r = getRed(p) setRed(p,r-(r%4)) # Clear out the green 2xLSB g = getGreen(p) setGreen(p,g-(g%4)) # Clear out the blue 2xLSB b = getBlue(p) setBlue(p, b-(b%4))

pixels = getPixels(picture) for charIndex in range(0, len(message)): characterVal = (ord(message[charIndex])-65)

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#Special case space symbol if ord(message[charIndex])==32: characterVal = 55

#Convert the number into a binary representation binaryValues = [0,0,0,0,0,0] index = 5 while characterVal>0: binaryValues[index] = ((characterVal%2)) characterVal = characterVal/2 index= index-1

#Encode the values into the picture redVal = binaryValues[1] redVal = redVal+ 2*binaryValues[0]

greenVal = binaryValues[3] greenVal = greenVal+ 2*binaryValues[2]

blueVal = binaryValues[5] blueVal = blueVal+ 2*binaryValues[4]

r = getRed(pixels[charIndex]) setRed(pixels[charIndex],r+redVal) g = getGreen(pixels[charIndex])

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setGreen(pixels[charIndex],g+greenVal) b = getBlue(pixels[charIndex]) setBlue(pixels[charIndex],b+blueVal)

return picture (b) Now write a function to decode the original text. def decodeMessage(picture): secretMessage = "" charIndex = 0 for p in getPixels(picture): r = getRed(p)%4 g = getGreen(p)%4 b = getBlue(p)%4 binaryValues = [0,0,0,0,0,0] #Translate the values into binary if not r==0: if r==1: binaryValues[1] = 1 elif r==2: binaryValues[0] = 1 elif r==3: binaryValues[0]=1 binaryValues[1]=1 if not g == 0: if g==1: binaryValues[3] = 1 elif g==2: binaryValues[2] = 1 elif g==3: binaryValues[2]=1 binaryValues[3]=1 if not b == 0: if b==1: binaryValues[5] = 1 elif b==2: binaryValues[4] = 1 elif b==3: binaryValues[4]=1 binaryValues[5]=1

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binaryValues.reverse() characterValue = 0 multiple = 1 for index in range(0, 6): characterValue = characterValue+(multiple)*binaryValues[index] multiple = multiple*2 #Special Case Space value if not characterValue==55: secretMessage = secretMessage+ (chr(characterValue+65)) else: secretMessage = secretMessage + " " return secretMessage Note: Unless you pass along a message length, the end of the message will have a great number of extra capital A values.

12.19 We can be trickier about how we encode text. Imagine that you (the sender) of the message and the receiver have a hidden sentence containing all the characters you might need in a coded message, like “The quick brown fox jumps over the lazy cat.” You can now just encode the position of the character you want in the picture (e.g., a “t” could be 0 and an “h” could be 1). You don’t even need six bits for this encoding. Rewrite the encoding and decoding function from the last exercise to use a hidden sentence for encoding.

Note: In the example the question gives, all the characters are encoded as their lower case values, and that’s how the answer below does it. However, one could leave this section out and still answer the spirit of the question. def encodeMessage2(picture, message, codephrase): codephrase = codephrase.lower() #Go through all pixels and erase the lower two bits for p in getPixels(picture): # Clear out the red 2xLSB r = getRed(p) setRed(p,r-(r%4)) # Clear out the green 2xLSB g = getGreen(p) setGreen(p,g-(g%4)) # Clear out the blue 2xLSB b = getBlue(p) setBlue(p, b-(b%4)) pixels = getPixels(picture)

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for charIndex in range(0, len(message)): characterVal = (codephrase.find(message[charIndex].lower())) #Convert the number into a binary representation binaryValues = [0,0,0,0,0,0] index = 5 while characterVal>0: binaryValues[index] = ((characterVal%2)) characterVal = characterVal/2 index= index-1 #Encode the values into the picture redVal = binaryValues[1] redVal = redVal+ 2*binaryValues[0] greenVal = binaryValues[3] greenVal = greenVal+ 2*binaryValues[2] blueVal = binaryValues[5] blueVal = blueVal+ 2*binaryValues[4] r = getRed(pixels[charIndex]) setRed(pixels[charIndex],r+redVal) g = getGreen(pixels[charIndex]) setGreen(pixels[charIndex],g+greenVal) b = getBlue(pixels[charIndex]) setBlue(pixels[charIndex],b+blueVal) return picture def decodeMessage2(picture, codephrase): secretMessage = "" charIndex = 0 for p in getPixels(picture): r = getRed(p)%4 g = getGreen(p)%4 b = getBlue(p)%4 binaryValues = [0,0,0,0,0,0] #Translate the values into binary if not r==0: if r==1: binaryValues[1] = 1 elif r==2:

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binaryValues[0] = 1 elif r==3: binaryValues[0]=1 binaryValues[1]=1 if not g == 0: if g==1: binaryValues[3] = 1 elif g==2: binaryValues[2] = 1 elif g==3: binaryValues[2]=1 binaryValues[3]=1 if not b == 0: if b==1: binaryValues[5] = 1 elif b==2: binaryValues[4] = 1 elif b==3: binaryValues[4]=1 binaryValues[5]=1 binaryValues.reverse() characterValue = 0 multiple = 1 for index in range(0, 6): characterValue = characterValue+(multiple)*binaryValues[index] multiple = multiple*2 secretMessage = secretMessage+ codephrase[characterValue] return secretMessage

Chapter 13 13.1 Your father calls you. “My tech support people are saying that the company Web site is down because the database program is broken. What does the database have to do with our company Web site?” You explain to him how databases can be integral to running large Web sites. Explain both (a) how the Web site comes to be authored through the database and (b) how the HTML is actually created. a.) A website is constructed by a web browser from information stored on a server’s database. The server informs the web browser on what to display via HTML. b.) An HTML documted is created typically by a human web designer in some sort of

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text editor, who may work with various cascading style sheets (CSS files) and other tools besides simply writing HTML documents to compose a website.

13.2 You have a new computer that seems to connect to the Internet but when you try to go to http://www.cnn.com you get a “Server Not Found” error. You call tech support and they tell you to try to go to http://64.236.24.20. That works. Now both you and the tech know what’s wrong with your computer’s settings. What isn’t working properly, since you can get to a site via the Internet but can’t get the domain name www.cnn.com to be recognized?

It is most likely to be the database server address cache, this browser cache allows a browser to go directly to an IP Address without needing to check with the domain server (in this case cnn.com). However, if this cache is wrong or out of date it can cause issues.

(Source: http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.help.sqlanywhere.12.0.1/d badmin/finding-sa-tcpip.html)

13.3 Given a folder with images in it, create an index HTML page with links to each image. Write a function that takes a string which is the path to a directory.

You will create a page in the folder named index.html that should be an HTML page containing a link to every JPEG file in the directory. You will also generate a thumbnail (half the size) copy of each image. Use makeEmptyPicture to create a blank picture of the right size, then scale down the original picture into the blank picture. Name the new image “half-” + the original filename (e.g., if the original filename was fred.jpg, save the half-size image as half-fred.jpg). The anchor in the link to each full-size picture should be the half-size image. def createThumbnailSite(directory): indexFile = open(directory+"/index.html", "wb") for file in os.listdir(directory): if file.endswith(".jpg"): pic = makePicture(directory+"/"+file) width = getWidth(pic) height= getHeight(pic) newPic = makeEmptyPicture(width/2, height/2) sourceX = 0 for x in range(0, width/2): sourceY = 0 for y in range(0, height/2): color = getColor(getPixel(pic, sourceX, sourceY)) setColor(getPixel(newPic,x, y), color) sourceY = sourceY+2 sourceX = sourceX+2

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writePictureTo(newPic, directory+"/half-"+file) lStart = "<a href=\""+file+"\">" lMid = "<img src=\""+"half-"+file +"\">" lEnd = "</a>" indexFile.write(lStart+lMid+lEnd) indexFile.close()

13.4 Use your favorite search engine to figure out what are the differences between SGML, HTML 5, XML, HTML 4.01, and XHTML. SGML= Standard Generalized Markup Language is a standard for how to specify a document markup language or tag set.

HTML 5= The core technology markup language of the internet used for structuring and presenting content for the World Wide Web. XML= A markup language that defines a set of rules for encoding documents in a format which is both human readable and machine readable.

HTML 4.01= A version of the HyperText Makrup Language (HTML) that was the publishing language of the World Wide Web. It supported multimedia options, scritping languages, style sheets, better printing, and documents that were more accessible to users with disabilities. (Source: http://www.w3.org/TR/html401/) XHTML= Extensible Hypertext Makup Language is a family of XML markup languages that mirror or extend versions of HTML. It can be parsed like an XML file.

Therefore, the difference between each are: SGML and HTML 5= HTML is a descendant of SGML, but HTML 5 is particular is no longer close enough to SGML to be parsed with an SGML parser. But both are still markup languages. (http://en.wikipedia.org/wiki/Standard_Generalized_Markup_Language) SGML and XML & HTML 4.01 = XML directly extends SGML, but both disables many SGML options and adds additional restrictions. This is the same for HTML 4.01, though it is less restrictive than XML. (http://en.wikipedia.org/wiki/Standard_Generalized_Markup_Language) SGML and XHTML = Unlike HTML, XHTML is based on XML not SGML. Therefore XHTML can be thought of as a grandchild of SGML, or a much more restrictive version of it.

XML & XHTML and HTML 5 & HTML 4.01 = XML and XHTML can br thought of as one branch off from SGML, while HTML 4.01 and HTML 5 represent another. Each has there own restrictions and capabilities, though XHTML shares more with the HTML group than XML. HTML 4.01 and HTML5 = There are different versions of the same markup language,

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with HTML5 having slightly more capabilities, and no longer being SGML parsable.

XML and XHTML = XHTML is an extension of XML that mirrors or extends HTML, which means that XHTML is a variation off of XML with HTML elements.

13.5 Convert the following hexadecimal numbers to decimal: 2A3, 321, 16, 24, F3.

2A3=675 321=801 16=22 24=36 F3=243

13.6 Convert the following decimal numbers to hexadecimal: 113, 64, 129, 72, 3.

113=71 64=40 129=81 72=48 3=3

13.7 Convert the following colors to hexadecimal: gray, yellow, pink, orange, and magenta. You can get the red, green, and blue values for each color using print color.

Note: This entirety depends upon the specific version of each color chosen.

Gray= For a gray color, the only consideration is that all red, green, and blue values be the same. Therefore the three pairs of values need only be the same and not the minimum (which would be black) or the maximum (which would be white). Therefore the answer can range from 010101 to FEFEFE. Yellow = Yellow is a mix of red and green. That means that any value of equal red and green, especially higher values, will work. FFFF00 will be the typical answer, but even values down to CCCC00 will look yellow.

Pink= Pink is a bit more varying, however as long as there are decreasing values of red, blue, and green it can still be recognized. FF69B4 is the most typical example.

Orange = Orange is a mix of red and green, with a bit over half the value of green as red.

Therefore, the most typical solution will be something like FFA500. Any value of blue would very quickly make the color appear not orange.

Magenta = Magenta is always max red and max blue with no green. That means that the correct answer is FF00FF.

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13.8 The makeCatalog function that we create in this chapter has a couple of significant errors.

There should be a space in the title after the colon and before the product name. Fix that.

• The grammar of the example is awful, because the product we provided is plural (“Seahorses”) but the text assumes a singular product. Fix it so that the text is right for the number of the input. There are several ways to fix this problem. One way is to take in a boolean input for singular or plural, then change the text accordingly. Another way is to create two catalog page generators, one for singular and one for plural, then let the user decide which to use. Implement one of these.

•

1. Pass in a boolean: def makeCatalog(product, image, price, plural): file = open(getMediaPath("catalog.html"), "wt") body = "" if not plural: body = "<!DOCTYPE <html><html><head><title >Catalog Page for: "+product + "</title></ head ><body><h1>"+product+" is the greatest!</h1> <p>You are so lucky to have found this page! You have the opportunity to buy "+product+" for the low, low price of $"+str(price)+". Just take a look at this beauty! <img src=" +image+" height = 100></p> <p>Get one today!</p></ body > </html>" else: body = "<!DOCTYPE <html><html><head><title >Catalog Page for: "+product + "</title></ head ><body><h1>"+product+" are the greatest!</h1> <p>You are so lucky to have found this page! You have the opportunity to buy "+product+" for the low, low price of $"+str(price)+". Just take a look at these beauty! <img src=" +image+" height = 100></p> <p>Get some today!</p></ body > </html>" file.write(body) file.close() 2. Split it into two generators: def makeCatalogSingular(product, image, price, plural): file = open(getMediaPath("catalog.html"), "wt") body = "<!DOCTYPE <html><html><head><title >Catalog Page for: "+product + "</title></ head ><body><h1>"+product+" is the greatest!</h1> <p>You are so lucky to have found this page! You have the opportunity to buy "+product+" for the low, low price of $"+str(price)+". Just take a look at this beauty! <img src=" +image+" height = 100></p> <p>Get one today!</p></ body > </html>" file.write(body) file.close()

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def makeCatalogPlural(product, image, price, plural): file = open(getMediaPath("catalog.html"), "wt") body = "<!DOCTYPE <html><html><head><title >Catalog Page for: "+product + "</title></ head ><body><h1>"+product+" are the greatest!</h1> <p>You are so lucky to have found this page! You have the opportunity to buy "+product+" for the low, low price of $"+str(price)+". Just take a look at these beauty! <img src=" +image+" height = 100></p> <p>Get some today!</p></ body > </html>" file.write(body) file.close()

13.9 The makeSamplePage function generates all of the HTML on one line.

Inserting the character \n will generate new lines. Put in some newline characters into a new version of that function to create readable HTML. Call it makeReadableSamplePage. import os def makeSamplePage(directory): samplesFile=open(directory+"/samples.html","wt") samplesFile.write(doctype()) samplesFile.write(title("Samples from "+directory)+"\n") #Now, let's make up the string that will be the body samples="<h1>Samples from "+directory+" </h1>\n" for file in os.listdir(directory): if file.endswith(".jpg"): samples=samples+"<p>Filename: "+file samples=samples+'<image src=" '+file+' "height="100"></p>\n' samplesFile.write(body(samples)+"\n") samplesFile.close()

13.10 Write a function image that takes an image filename or URL, and a width, then returns the correct img tag for displaying that filename with a given width.

Rewrite makeSamplePage to use your new image function for generating the ing tag for the samples. import os def image(file): return '<image src=" '+file+' "height="100"></p>' def makeSamplePage(directory): samplesFile=open(directory+"/samples.html","wt") samplesFile.write(doctype()) samplesFile.write(title("Samples from "+directory)+"\n") #Now, let's make up the string that will be the body samples="<h1>Samples from "+directory+" </h1>\n "

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for file in os.listdir(directory): if file.endswith(".jpg"): samples=samples+"<p>Filename: "+file samples=samples+image(file)+"\n" samplesFile.write(body(samples)+"\n") samplesFile.close()

13.11 Write a function to create a simple home page with your name, your picture, and a table with the titles of your courses and teacher names. def simpleHomePage(name, img, courses, teacherNames): homePageFile=open("homepage.html","wt") samplesFile.write(doctype()) samplesFile.write(title("Homepage")+"\n") #Now, let's make up the string that will be the body bodyText="<h1>"+name+"</h1> \n" bodyText+= image(img)+"\n" bodyText += "<p>I am taking the classes:</p>\n" #Assumes courses and teacherNames are lists of same length for index in range(0, len(courses)): bodyText+= "<p>"+courses[index]+" with "+teacherNames[index]+"</p> \n" samplesFile.write(body(bodyText)+"\n") samplesFile.close()

13.12 Write a function called riddle that returns a two line string, with a riddle and its answer. Modify makeHomePage to insert the riddle at the end of the page rather than the tagline.

Note: This simply involves changing the tagline method on page 368 to be about riddles instead. import urllib import random def makeHomePage(name,interests): file=open(getMediaPath("homepage.html"),"wt") file.write( doctype ()) file.write(title(name+"'s Home Page")) text = "<h1>Welcome to "+name+"'s Home Page</h1> " text += "<p>Hi! I am "+name+". This is my home page!" text += " I am interested in "+interests+"</p>" text += "<p>Random riddle of the day: "+riddle()+"</p>" file.write(body(text)) file.close()

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def riddle(): riddles = [] riddles += ["What can you catch, but not hold?\nA cold."] riddles += ["What belongs to you but others use it more?\nYour name."] riddles += ["What kind of stones are never found in the ocean?\nDry ones."] riddles += ["What do elves do after school?\nGnomework."] riddles += ["Why did the chicken cross the road?\nTo get to the other side."] return random.choice(riddles)

13.13 Write a function to create a simple home page with your name, your picture, and your hometown. Provide a link to your home town in a search engine (like Google or Bing) and to a map of your home town (e.g., via Google Maps or Mapquest).

Note: Embedding a map from Google Maps or Mapquest of a home town will require an API key from one of those services. That APIKey could then be passed in to the function as well. For example, the below: def simpleHomePage(name, img, hometown, hometownlink, maplink, apikey): homePageFile=open("homepage.html","wt") samplesFile.write(doctype()) samplesFile.write(title("Homepage")+"\n") #Now, let's make up the string that will be the body bodyText="<h1>"+name+"</h1> \n" bodyText+= image(img)+"\n" bodyText += "<p>My hometown is "+hometown+"</p>\n" bodyText += '<p>You can learn more about it <a href="'+hometownlink+'"> here</a></p>\n' bodyText += '<iframe width="600" height="450" frameborder="0" style="border:0" src='+maplink+'&key='+apikey+'"></iframe>"' samplesFile.write(body(bodyText)+"\n") samplesFile.close() Note: Alternativey, an answer could simply include an image map of their hometown, which wouldn’t allow for interaction but wouldn’t require a key. def simpleHomePage(name, img, hometown, hometownlink, map): homePageFile=open("homepage.html","wt") samplesFile.write(doctype()) samplesFile.write(title("Homepage")+"\n") #Now, let's make up the string that will be the body bodyText="<h1>"+name+"</h1> \n" bodyText+= image(img)+"\n" bodyText += "<p>My hometown is "+hometown+"</p>\n"

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bodyText += '<p>You can learn more about it <a href="'+hometownlink+ '">here</a></p>\n' bodyText += "<p>And here's a map!</p>" bodyText += ""+image(map) samplesFile.write(body(bodyText)+"\n") samplesFile.close()

13.14 Go to www.half.com and look up a popular movie that they sell as a DVD. What database tables and fields do you think are needed to represent the data for a DVD? For each individual DVD on half.com a lot of information needs to be stored. This includes the name of the DVD, a synopsis, the format, the Director, the year the DVD was released. The most likely place to use a table would be the individual offers, which will have columns for quality, price, delivery date, seller, feedback, and comments.

13.15 Why should you use a relational database? Are there other kinds of databases? Who invented relational databases?

You should use relational databses because they allow for complex relationships to be represented (Source: Chapter 13, Page 371).

Yes there are other types of databases, including navigational databases (that store information hierarchically) and post-relational databases (though these are less than successful). (Source: http://en.wikipedia.org/wiki/Database#1960s.2C_navigational_DBMS) The concept for relational databses was proposed by E.F. Codd in 1970. (http://en.wikipedia.org/wiki/Relational_database)

13.16 Do some Web searches to come up with answers to these questions about relational databases: •What is a data base table?

In relational databases and flat file databases, a table is a set of data elements (values) using a model of vertical columns (which are identified by their name) and horizontal rows, the cell being the unit where a row and column intersect. A table has specified number of columns, but can have any number of rows. (Source: http://en.wikipedia.org/wiki/Table_%28database%29) •What is a join?

Join is an SQL clause that combines records from two or more tables in a relational database. (Source: http://en.wikipedia.org/wiki/Join_%28SQL%29)

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•What is a query?

The most common operation in relational databases, it retrieves data from one or more tables, or expressions. (Source: http://en.wikipedia.org/wiki/SQL) • What is a connection?

The connection is the means by which a database server and its client software communicate with each other. (Source: http://en.wikipedia.org/wiki/Database_connection)

13.17 Do some Web searches to come up with answers to these questions about SQL: •What is SQL?

A special-purpose programming language designed for managing data held in a relational database management system. (Source: http://en.wikipedia.org/wiki/SQL) •How do you create a table in SQL?

Note: In SQL, the answer would be: With the command “CREATE TABLE table_name” where table_name is the name of the specific table. (Source: http://www.w3schools.com/sql/sql_create_table.asp) Note: In Jython the answer would be: create table tablename (columnname, datatype,…)

(Source: Chapter 13, Page 375) •How do you insert a row in a table in SQL? Note: In SQL, the answer would be: There are two different ways to insert rows into a table. The first is to pass in all the values of the row: INSERT INTO table_name VALUES (value1, value2, value3,…); The other way to insert a row is to specify each of the columns that the values passed in map to. This allows insertion into a row without having to fill in information for each column of the row.

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INSERT INTO table_name VALUES (value1, value2, value3,…); (Source: http://www.w3schools.com/sql/sql_insert.asp) Note: In Jython the answer would be: insert into tablename values (columnvalue1, columnvalue2,…)

(Source: Chapter 13, Page 375) •How do you get data from a table in SQL? Note: In SQL the answer would be: There are two different ways, both involving the SELECT command. You can use: SELECT column_name, column_name2,…

FROM table_name; To grab an arbirtrary number of columns from a table with the name table_name, or you can use SELECT * FROM table_name; To select all the columns at once.

(Source: http://www.w3schools.com/sql/sql_select.asp) Note: In Jython the answer would be: Select * from tablename Select column_name1, column_name2,… from tablename Select * from tablename where condition Select column_name1, column_name2,… from tablename where condition (Source: Chapter 13, Page 376)

13.18 Write a function that reads delimited strings from a file with names and phone numbers and uses a database to store the names as the keys and the phone numbers as the values. Take as input the filename and the name of the person who’s phone number you are looking for. How would you look up the phone number to find the name it belongs to?

Note: This question does not specify the type of delimited strings to use, but the most common assumption would be a comma-delimited string. By relational database it could mean a relational database with hash tables, like in Program 165, or a MySQL database (which would requite the steps outlined on page 375 of Chapter 13). The former would lead to an answer like findPhoneNumber, and the latter would lead to an answer like

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findPhoneNumber2.

To answer the question, you would look up the phone number to find the name it belongs to by checking each of the keys to see if its value matches the phone number, then returning that name. import shelve from csv import * def findPhoneNumber(filename, personName): #Copy info to the database database = shelve.open(getMediaPath("phonenumbers.db"), "c") file = open(getMediaPath(filename), "rb") csvfile = reader(file) index = 0 for row in csvfile: thisRow = {'Name' : row[0], 'PhoneNumber': row[1]} database[str(index)] = thisRow index +=1 database.close() #Read info from the database to return the phone number phoneNumberToReturn = "Phone number not in database" database = shelve.open(getMediaPath("phonenumbers.db"), "r") for key in database.keys(): row = database[key] if row['Name'] == personName: phoneNumberToReturn = row['PhoneNumber'] return phoneNumberToReturn --from com.ziclix.python.sql import zxJDBC from csv import * def findPhoneNumber2(filename, personName): #Copy info to the database db =zxJDBC.connect("jdbc:mysql://localhost/test", "root", None , "com.mysql.jdbc.Driver") con = db.cursor() con.execute("create table Numbers (name VARCHAR(50), phonenumber VARCHAR(50))") file = open(getMediaPath(filename), "rb")

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csvfile = reader(file) for row in csvfile: con.execute("insert into Numbers values ("+row[0]+","+row[1]+")") #Read info from the database to return the phone number phoneNumberToReturn = "Phone number not in database" con.execute("select name,phonenumber from Numbers") for i in range(0, con.rowcount): results= con.fetchone() if results[0] == personName: phoneNumberToReturn = results[1] return phoneNumberToReturn

13.19 Create a relational database that has a person table, a picture table, and a person–picture table. In the person table, store an id, the person name, and the person’s age. In the picture table, store a picture id and filename. In the person– picture table, keep track of the people in each picture. Write a function that let you find all the pictures for people over a certain age.

Note: Since this answer refers to a single relational database with multiple tables, it has to be completed with SQL. from com.ziclix.python.sql import zxJDBC from csv import * #Returns a list of filenames for all pictures of people above the variable age def findAllPictures(age): #Grab the databse db =zxJDBC.connect("jdbc:mysql://localhost/test", "root", None , "com.mysql.jdbc.Driver") con = db.cursor() #Make the person table con.execute("create table Person (id INT, name VARCHAR(50), age INT)") #Make the picture table con.execute("create table Picture (id INT, filename VARCHAR(150))") #Make the person-picture table con.execute("create table PersonPicture (personid INT, pictureid INT)") #Copy Any information In #Read info from the database to return the picture list con.execute("select * from Person where age>"+str(age)) personIds = [] for i in range(0, con.rowcount):

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results= con.fetchone() personIds.append(results[0]) pictureIds = [] for id in personIds: con.execute("select * from PersonPicture where personId=="+str(id)) for i in range(0, con.rowcount): results = con.fetchone() pictureIds.append(results[1]) pictureFiles = [] for id in pictureIds: con.execute("select * from Picture where id=="+str(id)) for i in range(0, con.rowcount): results = con.fetchone() pictureFiles.append(results[1]) return pictureFiles

13.20 Create a relational database that has a product table, a customer table, an order table, and an order item table. In the product table, store an id, name, picture, description, and price. In the customer table, store the id, name, and address. In the order table, store the order id and customer id. In the order item table, store the order id, product id, and quantity. Write a function to let you find all orders for a given customer. Write a function to let you find all orders with a total cost greater than some specified value.

The commands to set up the tables for this answer are as follows: con.execute("create table Product (id INT, name VARCHAR(50), picture VARCHAR(100), description VARCHAR(500), price INT)") con.execute("create table Customer (id INT, name VARCHAR(50), address VARCHAR(100))") con.execute("create table Order (id INT, customerid INT)") con.execute("create table OrderItem (orderid INT, productid INT, quantity INT)") The function to let you find all orders for a given customer is as follows (assuming you are given customer name, if given customer id you can skip the first step): from com.ziclix.python.sql import zxJDBC from csv import * #Returns a list of filenames for all pictures of people above the variable age def findAllOrders(customerName): #Grab the databse db =zxJDBC.connect("jdbc:mysql://localhost/test", "root", None ,

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"com.mysql.jdbc.Driver") con = db.cursor() #Read info from the database to find the customer id con.execute("select id from Customer where name=="+str(customerName)) customerId for i in range(0, con.rowcount): results= con.fetchone() customerId = (results[0]) #Read info from database to find the orderIds stored for this customerid orderIds = [] con.execute("select id from Order where customerid=="+str(customerId)) for i in range(0, con.rowcount): results= con.fetchone() orderIds.append(results[0]) return orderIds The function to let you find all orders with a total cost greater than some specified value is as follows: Note: This requires a number of steps, as one can’t assume that each order only has a single entry in the OrderItem table. from com.ziclix.python.sql import zxJDBC from csv import * #Returns a list of filenames for all pictures of people above the variable age def findAllOrdersByCost(cost): #Grab the databse db =zxJDBC.connect("jdbc:mysql://localhost/test", "root", None , "com.mysql.jdbc.Driver") con = db.cursor() #Read info from database to find all orderIds orderIds = [] con.execute("select id from Order") for i in range(0, con.rowcount): results= con.fetchone() orderIds.append(results[0]) #Create a dictionary to store each order's information orderInformation ={} #Fill the dictionary with empty lists at first for id in orderIds:

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orderInformation[id] = [] #Read info from OrderItem table to fill in orderIds dictionary con.execute("select * from OrderItem") for i in range(0, con.rowcount): results= con.fetchone() #Store as a list in case each order has multiple products productId = results[1] quantity = results[2] orderInformation[results[0]].append([productId, quantity]) orderIdsAboveCost = [] #Iterate through order ids to sum up cost for id in orderIds: orderCost = 0 for productOrder in orderInformation: #Grab the products cost productCost = 0 con.execute("select price from Product where id=="+str(productOrder[0])) for i in range(0, con.rowcount): results= con.fetchone() productCost = int(results[0]) orderCost += productCost*int(productOrder[1]) if orderCost>cost: orderIdsAboveCost.append(id) return orderIdsAboveCost

13.21 Given a relational database with a person table that contains an id, name, and age. What do each of the following return?

•Select * from person.

This returns all the columns of the table “person”, which would be “id, name, and age”.

• Select age from person.

This returns just the column “age” from the table “person” • Select id from person.

This returns just the column “id” from the table “person”.

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•Select name, age from person.

This returns the columns “name”, and “age” from the table “person”.

•Select * from person where age > 20.

This returns all the rows from “person” where the “age” value is greater than 20.

•Select name from person where age < 20.

This returns all the values from the “name” column of “person” where the “age” value for that row is less than 20.

13.22 Use a hash table to store texting shortcuts and their definitions. For example, “lol” means “laugh out loud.” Use this hash table to decode a text message. Iterate through all the words in the text message input, and if any are found, replace them with their definitions. Return the decoded string.

Note: The exact number of texting shortcuts used in this answer is up to the individual, but at least a handful should be used to make the method usable. def decodeTextMessage(message): shortcuts = {} shortcuts["lol"] = "laugh out loud" shortcuts["tmi"] = "too much information" shortcuts["4"] = "for" shortcuts["4eva"] = "forever" shortcuts["afaik"] = "as far as I know" shortcuts["asap"] = "as soon as possible" shortcuts["b4"] = "before" shortcuts["bc"] = "because" shortcuts["bf"] = "boyfriend" shortcuts["brb"]="be right back" shortcuts["cu"] = "see you" shortcuts["dgaf"] = "don't give a *freak*" shortcuts["dl"] = "down low" shortcuts["rofl"] = "rolling on the floor laughing" shortcuts["u"] = "you" messageToReturn = "" splits = message.split(" ") for word in splits: if word in shortcuts.keys(): messageToReturn += shortcuts[word]+" " else: messageToReturn += word+" "

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#Remove the last space messageToReturn = messageToReturn [:-1] return messageToReturn

Chapter 14 14.1 How many frames would you need for a two-hour movie with a picture size of 1024 width by 728 height and 60 frames per second? How much disk space would this movie need if you stored every pixel’s color? Remember that each pixel would require 24 bits to store the color.

If its 60 frames per second it would take 432,000 frames.

It’d take 1024*728 = 745,472 pixels for a single frame, so (745,472)*(432,000) = 322,043,904,000 pixels for the entire movie. This is equivalent to 24*322,043,904,000 = 7,729,053,696,000 bits.

14.2 Look on the Internet for answers to these questions: •How do the AVI and QuickTime movie formats differ?

“The primary difference is in the native support for lossy MP4 codecs like H.264.”

QuickTime movie formats supports these encoders while AVI does not.

Additionally, the QuickTime movie format was developed by Apple while AVI was developed by Microsoft, AVI is still more popular due to widespread use, and AVI cannot have subtites. (Source: http://www.differencebetween.net/technology/difference-between-mov-vs-avi/) •How do they compare to MPEG4?

The QuickTime movie format was the basis for MPEG4, and therefore they have very few differences, except that MPEG4 is an industry standard and therefore is usable on more decides. MPEG4 shares all the differences between QuickTime movie format and AVI, and is additionally more widely spread. (Source: http://www.differencebetween.net/technology/difference-between-mov-and-mp4/) • When would you want to use each movie format?

You can use .MOV, the QuickTime movie format if your movie will only be played on Apple devices, MPEG4 if you want to reach a broad audience of devices, and you should not use AVI unless you have to due to an older device’s constraints as it is outdated.

14.3 Look up “persistence of vision” on the Internet and how it relates to making

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animations.

Persistence of vision is the theory where an afterimage is thought to persist for approximately one sixteenth of a second on the retina, and therefore the reason why the brain translates still images in a sequence with minor changes as movement. (Source: http://en.wikipedia.org/wiki/Persistence_of_vision)

14.4 Only the first example in this chapter uses the movie object. Rewrite any of the other example programs to create a movie object and return the movie object.

Note: For most examples this only involves adding the final two lines from program 170 onto the end of the example. def movingRectangle2(directory): for num in range (1 ,30): #29 frames canvas = makeEmptyPicture (300 ,250) #add a filled rect moving linearly addRectFilled(canvas ,num*10,num*5,50,50,red) # Let’s have one just moving around blueX = 100+ int(10 * sin(num)) blueY = 4*num+int(10* cos(num)) addRectFilled(canvas ,blueX ,blueY ,50,50,blue) # Now , write out the frame # Have to deal with single digit vs. double digit numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") if num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"//frame00.jpg"); return movie

14.5 Write a function to create a movie where one item is moving from the top to the bottom and another item is moving from the bottom to the top. def movingRectangle3(directory): for num in range (1 ,30): #29 frames canvas = makeEmptyPicture (300 ,250) #add a filled rect moving linearly addRectFilled(canvas,0,num*7,50,50,red) addRectFilled(canvas,0 ,200-num*7 ,50,50,blue) # Now , write out the frame # Have to deal with single digit vs. double digit numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") if num >= 10:

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writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"//frame00.jpg"); return movie

14.6 Write a function to create a movie where one item is moving from the left to the right and another item is moving from the right to the left. def movingRectangle4(directory): for num in range (1 ,30): #29 frames canvas = makeEmptyPicture (300 ,250) #add a filled rect moving linearly addRectFilled(canvas,num*8,0,50,50,red) addRectFilled(canvas,250-num*8 ,0,50,50,blue) # Now , write out the frame # Have to deal with single digit vs. double digit numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") if num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"//frame00.jpg"); return movie

14.7 Write a function to create a movie where one item is moving in a diagonal line from top left to bottom right and another item is moving from the right to the left. def movingRectangle5(directory): for num in range (1 ,30): #29 frames canvas = makeEmptyPicture (300 ,250) #add a filled rect moving linearly addRectFilled(canvas,num*8,num*7,50,50,red) addRectFilled(canvas,250-num*8 ,200-num*7,50,50,blue) # Now , write out the frame # Have to deal with single digit vs. double digit numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") if num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"//frame00.jpg"); return movie

14.8 Create a new movie that has two rectangles moving a random amount (from −5 to 5) in each direction in each frame.

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import random def movingRectangle6(directory): rect1X = 100 rect1Y = 125 rect2X = 150 rect2Y = 125 for num in range (1 ,30): #29 frames canvas = makeEmptyPicture (300 ,250) rect1X+= -5+random.random()*10 rect1Y+= -5+random.random()*10 rect2X+= -5+random.random()*10 rect2Y+= -5+random.random()*10 #add a filled rect moving linearly addRectFilled(canvas,rect1X,rect1Y,50,50,red) addRectFilled(canvas,rect2X,rect2Y,50,50,blue) # Now , write out the frame # Have to deal with single digit vs. double digit numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") if num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"//frame00.jpg"); return movie

14.9 Create a movie that has the frames slowly becoming sepia-toned from left-toright. Maybe you make sepia-toned the leftmost 10 columns of pixels in the first frame, then the leftmost 20 columns are made sepia-tones in the second frame, and so on.

Note: This makes use of the copy method from Program 173 def sepiaWipe(directory, picture): #if each frame has 10 pixels changed, max frame is width/10 width = getWidth(picture) height = getHeight(picture) for num in range (1 ,width/10): canvas = makeEmptyPicture (width,height) pic = sepiaTint(picture,(num-1)*10,num*10, 0, height) copy(pic, canvas, 0, 0) numStr=str(num) if num < 10:

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writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") if num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"/frame00.jpg"); return movie def sepiaTint(picture, xMin, xMax, yMin, yMax): #Convert section to grayscale for x in range(xMin, xMax): for y in range(yMin, yMax): p = getPixel(picture, x, y) value = getRed(p) + getBlue(p) + getGreen(p) value = value/3 setRed(p, value) setBlue(p, value) setGreen(p, value) #Loop through the picture and tint values for x in range(xMin, xMax): for y in range(yMin, yMax): p = getPixel(picture, x, y) redVal = getRed(p) blueVal = getBlue(p) #tint shadows if (redVal<63): redVal = redVal*1.1 blueVal = blueVal*0.9 #tint midtones if (redVal > 62 and redVal< 192): redVal = redVal*1.15 blueVal = blueVal*0.85 #tint highlights if (redVal> 191): redVal = redVal*1.08 if (redVal>255): redVal = 255 blueVal = blueVal*0.93 #set the new color values setRed(p, redVal) setBlue(p, blueVal)

14.10 Create a movie where an input picture becomes wider and wider with

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successive frames. For example, the first frame of the movie might just have the middle 5 columns of pixels, then the second frame might have the middle 10 columns of pixels, then 15 columns, and so on.

Note: This makes use of the copy and clip methods from Program 173 def wipeIn(directory, picture): #if each frame has 5 pixels changed, max frame is width/5 width = getWidth(picture) height = getHeight(picture) for num in range (1 ,width/5): canvas = makeEmptyPicture (width,height) column = num*5 clippedPicture = clip(picture, (width/2)-column/2, 0, column, height) copy(clippedPicture, canvas, 0, 0) numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") elif num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"/frame00.jpg"); return movie

14.11 Create a movie where an input picture becomes smaller with successive frames. Paste the whole picture into the first frame, then reduce the size by 5% in successive frames.

Note: An answer could just make use of the clip method for this, but since the instructions clearly state to reduce the size by a percentage, a better solution is to scale the whole image. def shrinkPicture(directory, picture): #if each frame has 5 percent changed, max frame is width/20 width = getWidth(picture) height = getHeight(picture) for num in range (1 ,width/20): canvas = makeEmptyPicture (width,height) percent = 1.0-(0.05*num) scaledPicture = scaleDown(picture, percent) copy(scaledPicture, canvas, 0, 0) numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") elif num >= 10:

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writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"/frame00.jpg"); return movie def scaleDown(picture, percentScale): width = getWidth(picture) height = getHeight(picture) newWidth = int(width*percentScale) newHeight = int(height*percentScale) canvas = makeEmptyPicture(newWidth, newHeight) for x in range(0, width): for y in range(0, height): xNew = int(x*percentScale) yNew = int(y*percentScale) if xNew<newWidth and yNew<newHeight: canvasPix = getPixel(canvas, xNew, yNew) pix = getPixel(picture, x, y) setColor(canvasPix, getColor(pix)) return canvas

14.12 Create a movie where an input picture becomes more cropped with successive frames. Paste the whole picture into the first frame. In the second frame, copy the whole picture, but make the 5 columns of pixels on the left and 5 columns on the right all white. In the second frame, make it 10 frames. def cropMovie(directory, picture): #if each frame has 10 changed, max frame is width/10 width = getWidth(picture) height = getHeight(picture) for num in range (1 ,width/10): canvas = makeEmptyPicture (width,height) croppedPicture = clip(picture, 5*num, 0, width-num*5, height) copy(croppedPicture, canvas, 0, 0) numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") elif num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"/frame00.jpg"); return movie

14.13 Create a function that takes a picture and creates a movie with the picture slowly turning into the negative from left-to-right. Maybe you do the leftmost 10

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columns of pixels in the first frame, then the leftmost 20 columns are made negative in the second frame, and so on. def invertWipe(directory, picture): #if each frame has 10 pixels changed, max frame is width/10 width = getWidth(picture) height = getHeight(picture) for num in range (1 ,width/10): canvas = makeEmptyPicture (width,height) pic = invertColor(picture,(num-1)*10,num*10, 0, height) copy(pic, canvas, 0, 0) numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") elif num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"/frame00.jpg"); return movie def invertColor(picture, xMin, xMax, yMin, yMax): #Convert section to grayscale for x in range(xMin, xMax): for y in range(yMin, yMax): p = getPixel(picture, x, y) setRed(p, 255-value) setBlue(p, 255-value) setGreen(p, 255-value)

14.14 One of the most common transitions in movies is fade to black. Let’s implement that. Take a picture as input and copy that into the first frame of the movie. For the next 5 frames, copy the picture but make every 10th pixel black.

Then for the next 5 frames, make every 9th and 10th pixel black. Continue the process until all the pixels are black. def fadeToBlack(directory, picture): #if each frame has 10 pixels changed, max frame is width/10 width = getWidth(picture) height = getHeight(picture) for num in range (1 ,10): canvas = makeEmptyPicture (width,height) copy(pic, canvas, 0, 0) val = 10-num+1 makeBlack(canvas, val)

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numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") elif num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"/frame00.jpg"); return movie def makeBlack(picture, val): pixels = getPixels(picture) for increase in range(val, 11): for pixelIndex in range(0, len(pixels), increase): setColor(pixels[pixelIndex], makeColor(0,0,0))

14.15 Find another slide transition in PowerPoint or Keynote or some other presentation software, and implement it as a movie.

Note: This can be anything that someone can change iteratively. An easy answer to this question is to take a function from an earlier chapter and to adapt it to accept a variable for an amount to alter a picture.

14.16 Create a new version of the lineDetect function (Program 55 (page 128)) that takes in a threshold and create a movie using lineDetect where the threshold changes depending on the frame number. def edgeDetect(directory, picture): width = getWidth(picture) height = getHeight(picture) for num in range (1 ,10): canvas = makeEmptyPicture (width,height) copy(pic, canvas, 0, 0) val = 10-num+1 edgedetect(canvas, val) numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") elif num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"/frame00.jpg"); return movie def luminance(pixel): r = getRed(pixel) g = getGreen(pixel) b = getBlue(pixel) return (r+g+b)/3

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def edgedetect(source, threshold): for px in getPixels(source): x = getX(px) y = getY(px) if y < getHeight(source)-1 and x < getWidth(source)-1: botrt = getPixel(source ,x+1,y+1) thislum = luminance(px) brlum = luminance(botrt) if abs(brlum -thislum)> threshold: setColor(px,black) if abs(brlum -thislum)<=threshold: setColor(px,white)

14.17 Write a function that draws a sun on the picture of a beach at different places on the picture in successive frames. The goal is to make it look like the sun is moving across the sky through the day.

Note: The sun tends to move in an arc across the sky from left to top center to right, depending on one’s perspective in the world. Therefore, making use of sin and cos for arcing movement makes the most sense. def makeSunCrossSky(directory): for num in range (1 ,30): #29 frames canvas = makePicture(getMediaPath("beach.jpg")) # Let's have the sun moving on an arc sunX = 100+ num*4 sunY = 100+int(-20* cos(num/8.0)) addOvalFilled(canvas ,sunX ,sunY ,50,50,yellow) # Now , write out the frame # Have to deal with single digit vs. double digit numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") elif num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"//frame00.jpg"); return movie

14.18 Write a function to make a movie with text that starts out large near the bottom of the movie and then moves up toward the top and gets smaller each time it moves up. You can create a font style using makeStyle(family,type,size). def shrinkText(directory): for num in range (1 ,30): #29 frames canvas = makeEmptyPicture(320, 240) #Make the font and write the text

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font = makeStyle(sansSerif, plain, 30-num) addTextWithStyle(canvas,0, 200-num*4, "Hello World", font) # Have to deal with single digit vs. double digit numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") elif num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"//frame00.jpg"); return movie

14.19 Take a movie of some of your friends dancing in front of a green screen and use chromakey to make it look like they are dancing on the beach.

Note: One can just slightly alter Program 179 of Chapter 14 to accomplish this.

14.20 Take a movie of a location and a movie shot in front of a green screen and use chromakey to blend the two movies together.

Note: Changing Program 179 of Chapter 14 slightly is the easiest way to accomplish this, as below. import os def combineTwoVideos(directory, videoDirectoryOne, videoDirectoryTwo): frames = [] #Grab all the frames of the first video for frameFile in os.listdir(videoDirectoryOne): if frameFile.endswidth(".jpg"): frames.append(makePicture(videoDirectoryOne+"//"+frameFile)) num = 0 for frameFile in os.listdir(videoDirectoryTwo): num = num + 1 printNow("Frame: "+str(num)) if frameFile.endswith(".jpg"): frame=makePicture(videoDirectoryTwo+"//"+frameFile) for p in getPixels(frame): if distance(getColor(p),green) <= 100: setColor(p,getColor(getPixel(frames[num],getX(p),getY(p)))) writeFrame(num,directory ,frame)

14.21 Build an animation of at least three seconds in duration (30 frames at 10 fps, or 75 frames at 25 fps). You must have at least three things in motion during this

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sequence. You must use at least one composited image (a JPEG image that you scale (if necessary) and copy into the image) and one drawn image (a rectangle or line or text or oval or arc—anything that you draw). For at least one of the things in motion, change its velocity part way through the animation—change the direction or the speed.

Note: The important things to check here are that three different position values are changed for three different images, and that there is a check to change the velocity of one partway through the animation. An example is below: def movingImages (directory, img): imgX = 150 for num in range (1 ,30): #29 frames canvas = makeEmptyPicture (300 ,250) #add a filled rect moving linearly addRectFilled(canvas,num*8,num*7,50,50,red) addRectFilled(canvas,250-num*8 ,200-num*7,50,50,blue) if num>15: imgX +=num*3 else: imgX -= -num*3 copy(img, canvas, imgX, 0) # Now , write out the frame # Have to deal with single digit vs. double digit numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") elif num >= 10: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"//frame00.jpg"); return movie

14.22 http://abcnews.go.com is a popular news site. Let’s make a movie of it. Write a function that will input a directory as a string. Then: •Visit http://abcnews.go.com and pick out the top three news story headlines. (Hint: the anchors for the news story headlines all have <a href="/ wire/ before them. Find that tag, then search for the beginning of the anchor <a href="/wire/, then you can find the anchor text, which is the headline.)

• Create a ticker tape movie on the 640×480 canvas of all three news stories. Have

one come across at y = 100, another at y = 200, and the third at y = 300. Generate 100 frames, and don’t have the words move more than 5 pixels per frame. (In 100

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frames, you won’t make it all the way across the screen—that’s fine.) Store the frames to files in the input directory.

Note: This hint is no longer accurate. The current format is: <a href="/International/wireStory/report-china-manufacturing-lowest-year29857357". This makes it more difficult to answer this question, but not impossible. import urllib def movingArticles(directory): connect = urllib.urlopen("http://www.abcnews.go.com") news = connect.read() connect.close() #Grab the three articles template = 'wireStory/' indexOne = news.find(template) news = news[indexOne:len(news)] indexTwo = news.find('"') articleOne = news[len(template):indexTwo] news = news[indexTwo: len(news)] indexOne = news.find(template) news = news[indexOne:len(news)] indexTwo = news.find('"') articleTwo = news[len(template):indexTwo] news = news[indexTwo: len(news)] indexOne = news.find(template) news = news[indexOne:len(news)] indexTwo = news.find('"') articleThree = news[len(template):indexTwo] news = news[indexTwo: len(news)] #Replace the dashes with spaces and don't use the number articleOneList = articleOne.split("-") articleOne="" for index in range(0, len(articleOneList)-1): articleOne += articleOneList[index]+" " #Replace the dashes with spaces and don't use the number articleTwoList = articleTwo.split("-") articleTwo="" for index in range(0, len(articleTwoList)-1):

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articleTwo += articleTwoList[index]+" " #Replace the dashes with spaces and don't use the number articleThreeList = articleThree.split("-") articleThree="" for index in range(0, len(articleThreeList)-1): articleThree += articleThreeList[index]+" " for num in range (1 ,101): #100 frames canvas = makeEmptyPicture(640, 480) #Make the font and write the text font = makeStyle(sansSerif, plain, 30) addTextWithStyle(canvas,640-num*4, 100, articleOne, font) addTextWithStyle(canvas,640-num*4, 200, articleTwo, font) addTextWithStyle(canvas,640-num*4, 300, articleThree, font) # Have to deal with single digit vs. double digit numStr=str(num) if num < 10: writePictureTo ( canvas , directory +"//frame00"+ numStr +".jpg") elif num <=99: writePictureTo ( canvas , directory +"//frame0"+ numStr +".jpg") elif: writePictureTo ( canvas , directory +"//frame"+ numStr +".jpg") movie = makeMovieFromInitialFile(directory+"//frame00.jpg"); return movie

14.23 Create a movie where a person seems to be fading out of the scene. You can base this on the slowFadeout function (Program 177 (page 393)). def swapBack(pic1, newBg, threshold): for x in range(0,getWidth(pic1)): for y in range(0,getHeight(pic1)): p1Pixel = getPixel(pic1,x,y) if (distance(getColor(p1Pixel),green)< threshold*4): setColor(p1Pixel ,getColor(getPixel(newBg ,x,y))) return pic1 def personFadeout(directory): newBack = makePicture(getMediaPath("beach.jpg")) for num in range (1 ,60): #59 frames greenscale = makePicture(getMediaPath("greenscreen-person.jpg")) #Iteratively replace more of greenscale image (leading to fading person) replace(greenscale,newBack,num) # Now , write out the frame writeFrame(num,directory ,greenscale)

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movie = makeMovieFromInitialFile(directory+"//frame00.jpg"); return movie

14.24 Remember the blending of pictures in Chapter 6? Try blending one picture into another as a movie, slowly increasing the percentage of the second (incoming) image while decreasing the percentage of the original (outgoing) image.

14.25 The example of tracing bright pixels in this chapter used the paint1 folder in the mediasources. There is another example in paint2. Try running that one.

Note: This merely involves running Program 184 on the second folder.

14.26 The end-result pixels are pretty dull in the bright pixel tracing example. Use the makeLighter function to brighten up the pixels that you copy across.

Note: A one line addition is all that’s required for this. def brightCombine(fromDir ,target): fileList = allFiles(fromDir) fromPictFile = firstFile(fileList) fromPict = makePicture(fromDir+fromPictFile) for toPictFile in restFiles(fileList): printNow(toPictFile) # Copy all the high luminance colors from fromPict to toPict toPict = makePicture(fromDir+toPictFile) for p in getPixels(fromPict): if brightPixel(p): c = getColor(p) c = makeLighter(c) setColor(getPixel(toPict ,getX(p),getY(p)),c) writePictureTo(toPict ,target+toPictFile) fromPict = toPict

14.27 Will the bright pixel tracing function only work in darkness? Make your own movie with someone writing with a glow stick or flashlight, in normal brightness. Does the function still work? Do you need to use a different threshold value?

Do you have to try a different approach to identify “bright” pixels (e.g., perhaps by comparing luminance a particular pixel to the pixels around it)?

Note: Whether the functil will still work will highly depend on the video. If the video is in a fairly dim still, a bright light may still stand out enough to work with this approach, or by slightly altering the threshold value in brightPixel. However, if the scene is too bright then it will take more effort to distinguish the bright pixels. The option suggested above will work, and can be accomplished by passing in the pixel to the left and right and seeing if either of them are also bright.

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Chapter 15 15.1 Explain what the difference is between an interpreter and a compiler.

Interpreters just do the instructions, while compilers translate the program into another language (typically machine language) and then do the instructions. Compiling first means that the program runs faster. (Source: Chapter 15, Section 15.2.2)

15.2 What is machine language? How is it similar or different than bytecodes for the Java Virtual Machine? You will probably have to investigate on the Internet to answer these questions.

Machine Language is the lowest level programming language, and the one that many languages compile down to. (Source: http://www.webopedia.com/TERM/M/machine_language.html). The bytecodes for the Java Virtual Machine are different from machine language as they are explicit, set instructions (an individual is just 1 out of 256) for the Java Virtual Machine to execute.

They do not have, as machine language does, a one-to-one correspondence between the language and the architecture’s machine code instructions that the Java Virtual Machine is running on, since the Java Virtual Machine is an abstract computing machine.

15.3 Explain the difference between RAM and cache memory.

RAM (random access memory) is the main memory of the computer, while cache memory is a special memory used by the CPU to decrease the average time taken for memory access. RAM is where programs reside when they’re executing and its where the data your computer is acting on is located. Cache memory is more expensive than RAM. (Source: Chapter 15, Page 422)

15.4 There are lots of different kinds of sorting algorithms. Investigate some on the Internet. Which ones are considered fast, and under what conditions?

Note: An answer should at least mention the four sorts in questions 6-9.

Quicksort is considered to be very fast, but will not work well if passed an already sorted list, which is its worst-case scenario. Mergesort is also very fast, and can be faster than quicksort for types of list where the data to be sorted can only be efficially accessed sequentially. Insertion sort is not all that fast, but is a simple sorting algorithm. It is faster than bubble or selection sort. Bubble sort can be fast if the list is largely sorted with just a couple out of order pairs. Bogosort can take the least amount of time of any sort, but is hugely inefficient in the worst case, it randomizes a list until it is in order. Therefore, it can just return a list that’s in order without doing anything.

(Source: http://en.wikipedia.org/wiki/Sorting_algorithm#Comparison_of_algorithms)

15.5 Find animations of different sorting algorithms on the Internet. How would

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you describe difference between a bubble sort and a quicksort in terms of what you see in the animations?

Bubble sort creates a bubble of sorted list that expands out from the beginning of the list till the whole list is sorted. Quick sort jumps around the list.

15.6 Write a function to do an insertion sort on a list. def insertionSort(list): for i in range(0, len(list)): j=i while j>0 and list[j-1] >list[j]: jVal = list[j] list[j] = list[j-1] list[j-1] = jVal j = j-1 return list

15.7 Write a function to do a selection sort on a list. def selectionSort(list): for i in range(0, len(list)): iMin = i for j in range(i+1, len(list)): if list[j] < list[iMin]: iMin = j if not iMin == i: valI = list[iMin] list[iMin] = list[i] list[i] = valI return list

15.8 Write a function to do a bubble sort on a list. def bubbleSort(list): done = false while not done: swapped = false for i in range(1, len(list)): if list[i-1]>list[i]: iVal = list[i] list[i] = list[i-1] list[i-1] = iVal swapped = true if not swapped: done = true return list

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15.9 Write a function to do a quicksort on a list.

Note: This is by far the most difficult of the sorts to implement, as it involves recursion.

The choice of using a random index for the partition allows for fewer lines of code, as otherwise there are a number of special cases. For example, if an implementation always chose the middle, then it could run into infinite recusion if the list were (13, 2, 8), as everything would continue to be split into the larger list. import random def quickSort(list, depth): depth+=1 newList = [] if len(list)>1: partitions = partition(list) partial = quickSort(partitions[0], depth) partial2= quickSort(partitions[1], depth) for p in partial: newList.append(p) for p in partial2: newList.append(p) else: return list return newList def partition(list): pivotIndex = random.choice(range(0, len(list))) pivotValue = list[pivotIndex] smallList = [] largeList = [] for i in range(0, len(list)): if list[i]<pivotValue: smallList.append(list[i]) else: largeList.append(list[i]) return (smallList, largeList) 15.10 How many times will the following code print out the message? for x in range (0 ,5): for y in range (0 ,10): print "I will be good" 50 15.11 How many times will the following code print out the message?

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for x in range (1 ,5): for y in range (0 ,10 ,2): print "I will be good" 20 15.12 How many times will the following code print out the message? for x in range (0 ,3): for y in range (1 ,5): print "I will be good" 12

15.13 What is the Big-Oh of the method clearBlue?

Note: This question refers to Program 36, Chapter 4 page 94.

It is O(n), it occurs in linear time as it iterates through all the elements once.

15.14 What is the Big-Oh of the method lineDetect?

Note: This question refers to Program 55, Chapter 5, Page 128 It is O(n) as it iterates through all the elements once.

15.15 Trace through the binary search algorithm in findInSortedList given the following input. findInSortedList("8",["3","5","7","9","10"]) Loop 1. start = 0 end = 4 checkpoint = 2 alist[checkpoint] = “7” Action: start is set to one greater than checkpoint (3).

Loop 2 start = 3 end = 4 checkpoint= 3 alist[checkpoint] = “9” Action: end if set to one less than checkpoint (3).

Returns: “Not Found”

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15.16 Trace through the binary search algorithm in findInSortedList given the following input. findInSortedList("3",["3","5","7","9","10"]) Loop 1. start = 0 end = 4 checkpoint = 2 alist[checkpoint] =“7” Action: end is set to one less than checkpoint (1).

Loop 2. start = 0 end = 1 checkpoint = 0 alist[checkpoint] =“3” Action: returns “Found it!”

15.17 Trace through the binary search algorithm in findInSortedList given the following input. findInSortedList("1",["3","5","7","9","10"]) Loop 1. start = 0 end = 4 checkpoint = 2 alist[checkpoint] =“7” Action: end is set to one less than checkpoint (1).

Loop 2. start = 0 end = 1 checkpoint = 0 alist[checkpoint] =“3” Action end is set to one less than checkpoint (0).

Returns: “Not found”

15.18 Trace through the binary search algorithm in findInSortedList given the following input. findInSortedList("7",["3","5","7","9","10"])

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Loop 1. start = 0 end = 4 checkpoint = 2 alist[checkpoint] =“7” Action: returns “Found it!”

15.19 You’ve now seen some examples of class P problems (e.g., sorting and search- ing), intractable problems (optimization of the song elements), and class NP problems (e.g., the Traveling Salesman Problem). Search the Web and find at least one more example of each class of problem.

An example of a P problem would be to find the greatest common divisor of two numbers, or determining whether a number is prime. (Source: http://en.wikipedia.org/wiki/P_%28complexity%29) Intractable problems are not as well defined, but in general an example like recursive computation of Fibonacci numbers is a good example of an exponential algorithm.

An example of an NP problem would be the knapsack problem, which asks that you pack a knapsack of known size with masses, such that the knapsack is as full as possible while not going over the limit. (Source: http://en.wikipedia.org/wiki/Knapsack_problem)

15.20 Try something that takes a while in JES (e.g., chromakey on a large image).

Use the time module to time how long it takes. Now time the same JES task on several different computers with different amounts of memory and different clock rates (and different amounts of cache, if you can). See what difference the different factors make in terms of the time it takes to complete the task in JES. Note: Higher cache sizes will lead to faster computation, and various other factors will impact this as well, including RAM, the age of the computer, and how many other processes are running at the same time.

15.21 Alan Turing is known for another important finding in computer science, besides the proof that the Halting Problem is unsolvable. He gave us our test for whether a computer has actually achieved intelligence. What is the name of this test and how does it work? Do you agree that it is a test of intelligence?

The Turing Test is the name given to the test Turing proposed to determine if a computer has achieved intelligence. The test is also sometimes referred to as the conversation game, based on the party game in from which it derives. The test takes place with a human judge, and two unknown individuals, one a computer and the other a human. The human judge takes turns chatting to both the computer and the human via text. At the end, the human judge guesses which was a human and which was a computer. If a computer could beat out a human at this test, Turing supposed that would indicate it had

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achieved human intelligence.

There can be some argument, but the test is fairly clearly not a judgement of human level intelligence. For one thing, an AI chat agent has already beaten the test (passing the bare minimum requirements, not even fooling a majority of the judges), and computers can hardly be thought of as having human intelligence. Additionally, as demonstrated by the winning agent, the game quickly became just an attempt for human designers to create AI to “game” the test. For example, the winning agent was a chat agent programmed to pretend to be a non-native English speaker, and a young boy. This allowed it to excuse any inconsistencies in its behavior.

15.22 How do people get answers to problems that have algorithms that would take way too long to find the optimal result? Sometimes they use heuristics: rules that don’t lead to a perfect solution, but find a solution. Look up some heuristics used to compute the next move in a chess-playing program.

Some common heruistics involve capturing pieces, so capturing the last moved piece with the least valuable attacker, or capturing a piece with an equivalent piece. Other heuristics include assuming that the opposite player will not make the move in your best interest. (Source: https://chessprogramming.wikispaces.com/Move+Ordering)

15.23 Find an algorithm that solves the Traveling Salesman Problem in reasonable run time but isn’t optimal.

The Held-Karp algorithm would be an example of this. In a very abstract way this algorithm works by solving each and every subproblem, but finding the smallest distance between different points. This is non-optimal as the algorithm ends up solving problems it doesn’t need to. (http://en.wikipedia.org/wiki/Held%E2%80%93Karp_algorithm)

15.24 The program Watson successfully beat humans at the game Jeopardy. Find articles on the Internet that explain how Watson did it. Does it guarantee that it always finds the best solution?

Simple Article: http://www.quora.com/How-does-IBMs-Watson-work Complex Article: http://www.aaai.org/Magazine/Watson/watson.php Watson did it essentially through a rules-based system, though a much more complex one then the simple rules that have been written within these questions, along with fast look up of information. Watson does not guarantee to always find the best solution.

Chapter 16 16.1 Here’s a puzzle. You have six blocks. One of them weighs more than the other. You have a scale but you can only use it twice. Find the heaviest one. (a) Write down your process as an algorithm.

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1. Measure two of the blocks on one side and two of the blocks on the other. If the scale balances go to 3, if not go to 2.

2. Take the two blocks from the heavier side of the scale and weigh them against each other, the heavier of the two is the heaviest block.

3. Take the two blocks you didn’t weigh, and weigh them against each other, the heavier of the two is the heaviest block. (b) What search is this like?

This is like binary search, where the set of things to search through is repeatedly split till an answer is found.

16.2 Mathematicians talk about the Fibonacci Sequence, which is a series of numbers defined recursively. The first Fibonacci number is 0, and the second is 1.

From there on out, the nth Fibonacci number is Fib(n) = F ib(n − 2) + Fib(n − 1).

Write a function to input an integer index and then calculate that index value in the Fibonacci sequence. def Fib(index): if index<=1: return index else: return (Fib(index-2) + Fib(index-1))

16.3 Compound interest means that you add the interest (say, 2%) to a starting balance (say, $100) for a period of time (say it’s a year) to get a new balance ($102.00 in this example). During the next period of time, we apply the same interest rate to the new balance. In our example, during the second year, our 2% interest on $102 would give us $104.04 as our new balance. Write a function compound Interest that takes in an interest rate, a starting balance, and a number of years, then returns what the new balance would be. (Hint: Recursion can be useful here.) def compoundInterest(interestRate, balance, years): if years>0: years-=1 balance += balance*interestRate return compoundInterest(interestRate, balance, years) else: return balance

16.4 Write a function to convert Celsius to Fahrenheit. def cToF(temp): temp = temp*9 temp = temp/5.0

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temp = temp +32 return temp

16.5 Write a function to convert Farenheit to Celsius. def fToC(temp): temp = temp – 32 temp = temp* 5.0 temp = temp/9.0 return temp

16.6 If you have both of the last two functions (Celsius to Farenheit, and Farenheit to Celsius), are the exact inverses of one another? If you convert 32 degree Farenheit to Celsius, and then back to Farenheit, do you get 32 again? Try out different values. When does it work, and when doesn’t it and why?

Yes, you do get 32 with the call: fToC(cToF(32)) The values may be incorrect if the answers to the previous question made use of int division, or if one used one of the faster but less precise formulas.

16.7 Write a function to calculate a person’s body mass index given his/her weight and height.

Note: It is acceptable to assume that the weight has been given in kilograms and the height in meters for this question, as it is not specified otherwise. def calculateBMI(weight, height): return weight/(height*height) Note: However, if one does input the values in feet and pounds then the function should look more like: def calculateBMI(weight, height): height = height/3.2808 weight = weight/2.2046 return (weight/(height*height))

16.8 Write a function to calculate a tip of 20%.

Note: The simple way to do this is: def calculateTip(amount): return amount*0.2 Note: If you instead want to be sure that you don’t have an answer that includes anything under a penny, you could instead use (though it won’t round up):

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def calculateTip(amount): tip= amount*0.2 tipStr = str(tip) split = tipStr.split(".") if len(split)==2: tipStr = split[0] if(len(split[1])>2): tipStr += "."+split[1][0:2] else: tipStr+= "."+split[1] return tipStr

16.9 Change the functional turnHairRed() in Program 192 (page 433) into only a single line by recoding the utility functions as lambda functions. def turnHairRed(pic): map(lambda a: setRed(a,getRed(a)*2) ,filter(lambda a: distance(getColor(a),makeColor(42,25,15))<50.0 ,getPixels(pic)))

16.10 Describe what this function does. Try different numbers as input. def test(num): if num > 0: return test(num-1) else: return 0 The function recursively decrements a number till it hits 0, then returns 0. No matter what values you pass into it, it will always return 0 in the end.

16.11 Describe what this function does. Try different numbers as input. def test(num): if num > 0: return test(num-1) + num else: return 0 This method recursively calls itself with a decremented number, but adds that decremented number to the returned value till it hits 0. This causes it to return 3 for 2, 6 for 3, 10 for 4, and so on.

16.12 Describe what this function does. Try different numbers as input. def test(num): if num > 0: return test(num-1)*num

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else: return 0 This method recursively calls itself with a decremented number, and multiplies that decremented number to the returned value till it hits 0. This has the effect of it always returning 0 as 0 times anything is 0.

16.13 Describe what this function does. Try different numbers as input. def test(num): if num > 0: return num – test(num-1) else: return 0 This method recursively calls itself with a decremented number, and subtracts that call from that number each time. This has an interesting effect, displayed in the examples below: test(1) = 1 test(2) = 2-test(1) = 1 test(3) = 3-test(2) = 2 test(4) = 4-test(3) = 2 test(5) = 5-(test4) = 3 …

16.14 Describe what this function does. Try different numbers as input. def test(num): if num > 0: return test(num -2) * test(num -1) else: return 0 This method recursively calls itself by calling itself each time that the passed in num is above 0, with one cal decrementing the num once and one twice. None of this has any impact though as 0 times anything is still 0 so any number passed in will be 0.

16.15 Write a recursive method to list all the files in a directory and in all subdirectories.

Note: One can simply make use of Program 195 for this answer, or a few of the baked in methods of the os module. import os def listAll(directory):

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for dirname, dirnames, filenames in os.walk(directory): for f in filenames: printNow(f) for d in dirnames: listAll(d) 16.16 Try writing upDown(): >>> upDown("Hello") Hello Hell Hel He

H He Hel Hell Hello

Try to write upDown() both recursively and without recursion. Which is easier?

Why? Note: Given that output, one can presume that they were either printed out, or are one string with new line characters at the end of each line.

Recursively: def upDown(str): print str if len(str)>1: upDown(str[0:len(str)-1]) print str Without Recursion: def upDown(str): origStr = str while len(str)>0: print str str = str[0:len(str)-1] while len(str)<len(origStr): str += origStr[len(str)] print str Whether you think that doing this with or without recursion is easier largely depends on your familiarity with recursion. I found the recursive version much easier as there was less code to think through.

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16.17 Using map, increase the value of a sound by applying a function to each sample of the sound. def increaseValue(sound): map(increase,getSamples(sound)) def increase(sample): newVal = getSampleValue(sample) setSampleValue(sample,newVal*2)

16.18 Using map and filter, maximize a sound—if a sample’s value is greater than or equal to 0, make the sample value 32, 767, and if not, make it −32, 768.

Note: Since filter will only return elements that meet the method requirements, its necessary to have two methods: one to capture positive samples, and one to capture negative samples. def extremify(sound): map(maximize,filter(positiveSample, getSamples(sound))) map(minimize,filter(negativeSample, getSamples(sound))) def maximize(sample): setSampleValue(sample, 32767) def minimize(sample): setSampleValue(sample, -32767) def positiveSample(sample): val = getSampleValue(sample) if val>=0: return 1 else: return 0 def negativeSample(sample): val = getSampleValue(sample) if val<0: return 1 else: return 0 16.19 Try writing any other of our sound and picture examples from the earlier chapters functionally, using structures like filter and map.

Note: One of the easiest of these to do would be the decrease method from Program 94 of

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Chapter 7. def decrease(sound): map(decreaseSample,getSamples(sound)) def decreaseSample(sample): newVal = getSampleValue(sample) setSampleValue(sample,newVal*0.5)

Chapter 17 17.1 Look up Sierpinski’s triangle. Write a recursive function with turtles to create Sierpinski’s triangle.

Note: Sierpinski’s triangle is very similar to the result of nestedTri. Additionally, trying to turn the turtle to begin with to set the triangle up “correctly” will lead the turtle getting slightly off. def sierpinski(): earth = World(1000, 1000) suzy = Turtle(earth) nestedTri(suzy,250, 0) def nestedTri(t, size, depth): depth = depth+1 if depth >6: return for sides in range(3): nestedTri(t,size/2.0, depth) forward(t, int(size)) turn(t, 120) 17.2 Look up Koch’s snowflake. Write a recursive function with turtles to create Koch’s snowflake.

Note: The answer can’t go too “deep” since the turtles are imprecise (in that they have to use int values) def kochSnowflake(sides, size): earth = World(1000, 1000) suzy = Turtle(earth) for s in range(sides): kochCurve(suzy, size, sides-1) turn(suzy, int(360/float(sides))) def kochCurve(t, size, degree):

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if degree==0: forward(t, int(size)) else: kochCurve(t, size/3.0, degree-1) turn(t, -60) kochCurve(t, size/3.0, degree-1) turn(t, 120) kochCurve(t, size/3.0, degree-1) turn(t, -60) kochCurve(t, size/3.0, degree-1) 17.3 We can make all motions of a turtle slower by using a form of forward that includes sleep def pausedForward(turtle ,amount): sleep (0.2) turtle.forward(amount) Rewrite the chase and dance functions to use pausedForward. from time import sleep def chaseSlow (): # Set up the four turtles earth = World () al = Turtle(earth) bo = Turtle(earth) cy = Turtle(earth) di = Turtle(earth) al.penUp() al.moveTo(10,10) al.penDown() bo.penUp() bo.moveTo(10,400) bo.penDown() cy.penUp() cy.moveTo(400,10) cy.penDown() di.penUp() di.moveTo(400,400) di.penDown() # Now , chase for 300 steps for i in range (0 ,300): chaseTurtle(al,cy) chaseTurtle(cy,di) chaseTurtle(di,bo) chaseTurtle(bo,al)

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def chaseTurtle(t1,t2): t1.turnToFace(t2) pausedForward(t1, 4) def danceSlow (): makesquare() def makesquare (): w = makeWorld() evenlist = [] oddlist = [] for turtles in range (10): t = makeTurtle(w) t.turn(turtles*36) if turtles % 2 == 0: evenlist = evenlist + [t] else: oddlist = oddlist + [t] for times in range(20): for sides in range(5): if times % 2==0: for t in evenlist: pausedForward(t, 100) t.turn(90) else: for t in oddlist: pausedForward(t, 100) t.turn(72) sleep (0.2) def pausedForward(turtle ,amount): sleep (0.2) turtle.forward(amount) 17.4 We can get the same effect as sleep by playing a sound with blockingPlay. Change the dance code to use a brief sound to pause the dance, rather than sleep. def danceSound (sound): makesquare(sound) def makesquare (sound): w = makeWorld() evenlist = [] oddlist = [] for turtles in range (10): t = makeTurtle(w) t.turn(turtles*36)

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if turtles % 2 == 0: evenlist = evenlist + [t] else: oddlist = oddlist + [t] for times in range(20): for sides in range(5): if times % 2==0: for t in evenlist: t.forward(100) t.turn(90) else: for t in oddlist: t.forward(100) t.turn(72) blockingPlay (sound) 17.5 Now, use blockingPlay on different sounds to get music to go with the dance.

Note: The easiest way to answer this question is to play a sound on the even turn and a sound on the odd turn. def danceSound (sound1, sound2): makesquare(sound1, sound2) def makesquare (sound1, sound2): w = makeWorld() evenlist = [] oddlist = [] for turtles in range (10): t = makeTurtle(w) t.turn(turtles*36) if turtles % 2 == 0: evenlist = evenlist + [t] else: oddlist = oddlist + [t] for times in range(20): for sides in range(5): if times % 2==0: for t in evenlist: t.forward(100) t.turn(90) blockingPlay(sound1) else: for t in oddlist: t.forward(100) t.turn(72) blockingPlay (sound2)

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17.6 The techniques we used to create recursive triangles can be used with other figures as well. Create nested and corner versions of squares and of pentagons.

Note: All this question requires in an answer is to change the number of sides and angles for Program 205 and 206.

Squares: def nestedSquare(t,size): if size < 10: return for sides in range (4): nestedSquare (t,size/2) forward(t,size) turn(t,90) def cornerSquare(t,size): if size < 10: return for sides in range (4): forward(t,size) cornerSquare (t,size/2) turn(t,90) Nested Output (size 100):

Corners Output (size 100):

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Pentagons: def nestedPentagon(t,size): if size < 10: return for sides in range (5): nestedPentagon(t,size/2) forward(t,size) turn(t,72) def cornerPentagon(t,size): if size < 10: return for sides in range (5): forward(t,size) cornerPentagon(t,size/2) turn(t,72) Nested Output (80):

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Corner Output (80):

17.7 Answer the following questions about object-oriented programming, using this chapter and explorations on the Web. •What is the difference between an instance and a class?

A class is like a blueprint for an instance. The instance is the thing that we can make use of, while the class is just a set of instructions on how to make it.

(Source: Chapter 17, Page 449) •How are functions and methods different?

Functions are “outside” a class, while methods are “inside” a class. A method can only be called through an instance of a class, while a functil can be called without one.

(Source: Chapter 17, Page 454)

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•How is object-oriented programming different from procedural programming?

Procedural programming is programming with “verbs” while object-oriented programming is programming with “nouns”. Both are just styles for getting programs done, with procedural programming focusing on just creating functions that do things, and object oriented programming focusing on creating objects that do things.

(Source: Chapter 17, Pages 447-448) •What is polymorphism?

When the same name can be used to invoke different methods to achieve the same goal.

(Source: Chapter 17, Page 469) •What is encapsulation?

Encapsulation is a feature of object-oriented programming in which data and behaviors are accessible in one and only one place.

•What is aggregation?

Aggregation is a feature of object-oriented programming in which lots of different data can be stored in the same type of object, such that many objects are stored instead of many individual classes.

•What is a constructor?

A constructor is the method of a class that allows for the construction of a new instance of that class.

•How did biological cells influence the development of the idea of objects?

Alan Kay referred to them as an example of the way that computer science objects would work together like how cells work together to make a whole organism work.

(Source: Chapter 17, Page 448) 17.8 Answer the following questions about how objects work, using this chapter and explorations on the Web. •What is inheritance?

Inheritance is a feature of object oriented programming in which certain classes can inherit data and behavior from a “parent” class. They also allow for instant polymorphism.

(Source: Chapter 17, Page 476) •What is a super class?

The super class is the class from which another class inherits.

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(Source: Chapter 17, Page 476) •What is a sub class?

The sub class is the class that inherits from a super class.

(Source: Chapter 17, Page 476) •What methods does a child class inherit?

In Java, a subclass inherits all of the public and protected members of its parent (those that specifically make use of those specialized words in their definition). In Python, a subclass inherits all of the members from its parent class. (Source: https://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html and https://docs.python.org/2/tutorial/classes.html#inheritance) •What instance variables (fields) does a child class inherit?

(Same answer as the above) 17.9 Add a method to the Turtle class to draw an equilaterall triangle.

Note: By Turtle class this means a new sub class like SmartTurtle or ConfusedTurtle. class MyTurtle(Turtle): #Assumes the turtle starts looking straight up def drawTri(self, size=60): self.turn(30) for i in range(3): self.forward(size) self.turn(120) 17.10 Add a method to the Turtle class to draw a rectangle given a width and height.

Note: New method at bottom class MyTurtle(Turtle): #Assumes the turtle starts looking straight up def drawTri(self, size=60): self.turn(30) for i in range(3): self.forward(size) self.turn(120)

#Assumes the turtle starts looking straight up

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def drawRect(self, width=100, height = 100): self.turnRight() self.forward(width) self.turnRight() self.forward(height) self.turnRight() self.forward(width) self.turnRight() self.forward(height) 17.11 Add a method to the Turtle class to draw a simple house. It can have a rectangle for the house and an equilateral triangle as the roof.

Note: New method at bottom class MyTurtle(Turtle): #Assumes the turtle starts looking straight up def drawTri(self, size=60): self.turn(30) for i in range(3): self.forward(size) self.turn(120) #Assumes the turtle starts looking straight up def drawRect(self, width=100, height = 100): self.turnRight() self.forward(width) self.turnRight() self.forward(height) self.turnRight() self.forward(width) self.turnRight() self.forward(height) #Assumes the turtle starts looking straight up def drawHouse(self, width=100, height=100): self.drawRect(width,height) self.drawTri(width) 17.12 Add a method to the Turtle class to draw a street of houses.

Note: New method at bottom, and changed drawTri slightly to end with the turtle looking straight up. The drawHouses method could also have variables passed in to determine the make up of the street of houses instead of having them hardcoded in. class MyTurtle(Turtle):

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#Assumes the turtle starts looking straight up def drawTri(self, size=60): self.turn(30) for i in range(3): self.forward(size) self.turn(120) self.turn(-30) #Assumes the turtle starts looking straight up def drawRect(self, width=100, height = 100): self.turnRight() self.forward(width) self.turnRight() self.forward(height) self.turnRight() self.forward(width) self.turnRight() self.forward(height) #Assumes the turtle starts looking straight up def drawHouse(self, width=100, height=100): self.drawRect(width,height) self.drawTri(width) #Assumes the turtle starts looking straight up def drawHouses(self): self.penUp() self.moveTo(100, 100) self.penDown() self.drawHouse(100, 60) self.penUp() self.moveTo(300,100) self.penDown() self.drawHouse(80,60) self.penUp() self.moveTo(450,100) self.penDown() self.drawHouse(110,60) 17.13 Add a method to the Turtle class to draw a letter.

Note: Each individual method ends ensuring the turtle is looking straight up so that it will work for the assumptions made by the next method. class MyTurtle(Turtle): #Assumes the turtle starts looking straight up

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def drawM(self, size=60): self.forward(size) self.turn(150) self.forward(size) self.turn(-120) self.forward(size) self.turn(150) self.forward(size) self.turn(180) 17.14 Add a method to the Turtle class to draw your initials.

Note: Each individual method ends ensuring the turtle is looking straight up so that it will work for the assumptions made by the next method. class MyTurtle(Turtle): #Assumes the turtle starts looking straight up def drawM(self, size=60): self.forward(size) self.turn(150) self.forward(size) self.turn(-120) self.forward(size) self.turn(150) self.forward(size) self.turn(180) #Assumes the turtle starts looking straight up def drawJ(self, size=60): self.forward(size/4) self.backward(size/4) self.turn(90) self.forward(size/2) self.turn(-90) self.forward(size) self.turn(-90) self.forward(size/2) self.backward(size) self.turn(90) #Assumes the turtle starts looking straight up def drawG(self, size=60): x = self.getXPos() y = self.getYPos() self.turn(90) self.forward(size/2)

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self.turn(-90) self.forward(size/4) self.turn(-90) self.forward(size/8) self.penUp() self.moveTo(x,y) self.turn(90) self.penDown() self.forward(size) self.turn(90) self.forward(size/2) self.turn(90) self.forward(size/8) self.turn(180) #Assume the turtle starts looking up def drawInitials(self): self.penUp() self.moveTo(100, 150) self.penDown() self.drawM(100) self.penUp() self.moveTo(220, 150) self.penDown() self.drawJ(100) self.penUp() self.moveTo(340, 150) self.penDown() self.drawG(100) 17.15 Create a movie with several turtles moving in each frame, like our dance function.

Move each turtle, pause, and save it to a frame.

Note: The easiest way to do this is just to adapt Program 203 to write each frame to a directory. def dance (directory): return makesquare(directory) def makesquare (directory): w = makeWorld() evenlist = [] oddlist = [] for turtles in range (10): t = makeTurtle(w) t.turn(turtles*36)

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if turtles % 2 == 0: evenlist = evenlist + [t] else: oddlist = oddlist + [t] for times in range(20): for sides in range(5): if times % 2==0: for t in evenlist: t.forward(100) t.turn(90) else: for t in oddlist: t.forward(100) t.turn(72) val = times*5+sides if val < 10: writePictureTo(canvas,directory+"//frame00"+str(val)+".jpg") elif val>=10 and val<100: writePictureTo(canvas,directory+"//frame0"+str(val)+".jpg") else: writePictureTo(canvas,directory+"//frame"+str(val)+".jpg") movie = makeMovieFromInitialFile(directory+"//frame000.jpg"); return movie 17.16 Add another constructor to the Slide class that takes just a picture filename and plays no sound when it plays.

Note: The second constructor is simple to add, but also requires a check within the “show” method to avoid a Inappropriate argument exception class Slide: def __init__(self, pictureFile,soundFile): self.picture = makePicture(pictureFile) self.sound = makeSound(soundFile) def __init__(self, pictureFile): self.picture = makePicture(pictureFile) self.sound = None def show(self): show(self.picture) if not self.sound==None: blockingPlay(self.sound) 17.17 Create a SlideShow class that holds a list of slides and shows each slide one at a time.

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class SlideShow: def __init__(self, slideList): self.slides = slideList def show(self): for slide in self.slides: slide.show() 17.18 Create a CartoonPanel class that takes an array of Pictures and displays the pictures from left to right. It should also have a title and author, and display the title at the top left edge and the author at the top right edge. class CartoonPanel: def __init__(self, picturesArray, title, author): self.pictures = picturesArray sumWidth = 0 maxHeight = 0 for p in picturesArray: w = getWidth(p) h = getHeight(p) sumWidth = sumWidth+w if h>maxHeight: maxHeight = h canvas = makeEmptyPicture(sumWidth, maxHeight+50) currX = 0 for p in picturesArray: copy(p, canvas, currX, 50) currX =currX+ getWidth(p) canvas.addText(black, 1,20, title) canvas.addText(black, currX-100,20,author) self.panel = canvas def show(self): show(self.panel) def copy(source, target, targX, targY): targetX = targX for sourceX in range(0,getWidth(source)): targetY = targY for sourceY in range(0,getHeight(source)): px=getPixel(source ,sourceX ,sourceY) tx=getPixel(target ,targetX ,targetY) setColor(tx,getColor(px)) targetY=targetY + 1

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targetX=targetX + 1 17.19 Create a Student class. Each student should have a name and a picture. Add a method, show, that shows the picture for the student. class Student: def __init__(self, studentPic, studentName): self.picture = studentPic self.name = studentName def show(self): self.picture.show() 17.20 Add a field to the SlideShow class to hold the title and modify the show method to first show a blank picture with the title on it. class SlideShow: def __init__(self, slideList, title): self.slides = slideList self.title = title def show(self): titleScreen = makeEmptyPicture(300, 300) titleScreen.addTextWithStyle (black ,10,150,self.title, makeStyle(sansSerif, bold, 24)) titleScreen.show() for slide in self.slides: slide.show() 17.21 Create a PlayList class that takes a list of sounds and play them one at a time. class PlayList: def __init__(self, sounds): self.sounds = sounds def play(self): for s in self.sounds: blockingPlay(s) 17.22 Use the methods in the Picture class to draw a smiling face.

Note: One could make use of arc as in drawSmiley or circle (with part then “erased”) as in drawSmiley2 for the smile. def drawSmiley(): canvas = makeEmptyPicture(100,100) canvas.addArc(black, 10, 60, 80, 30, 160, 220) canvas.addOvalFilled(black, 10, 10, 20, 40) canvas.addOvalFilled(black, 70, 10, 20, 40)

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show(canvas) def drawSmiley2(): canvas = makeEmptyPicture(100,100) canvas.addOval(black, 10, 60, 80, 30) canvas.addRectFilled(white, 10, 60, 80, 10) canvas.addOvalFilled(black, 10, 10, 20, 40) canvas.addOvalFilled(black, 70, 10, 20, 40) show(canvas) 17.23 Use the methods in the Picture class to draw a rainbow.

Note: One could make use of arc as in drawRainbow or circle (with part offscreen or “erased”) as in drawRainbow2 for the smile. def drawRainbow(): canvas = makeEmptyPicture(100,100) canvas.addArcFilled(red, 0, 50, 100, 80, 0, 180) canvas.addArcFilled(orange, 5, 55, 90, 70, 0, 180) canvas.addArcFilled(yellow, 10, 60, 80, 60, 0, 180) canvas.addArcFilled(green, 15, 65, 70, 50, 0, 180) canvas.addArcFilled(blue, 20, 70, 60, 40, 0, 180) canvas.addArcFilled(makeColor(255, 0, 255), 25, 75, 50, 30, 0, 180) canvas.addArcFilled(white, 30, 80, 40, 20, 0, 180) canvas.show() def drawRainbow2(): canvas = makeEmptyPicture(100,100) canvas.addOvalFilled(red, 0, 50, 100, 100) canvas.addOvalFilled(orange, 5, 55, 90, 90) canvas.addOvalFilled(yellow, 10, 60, 80, 80) canvas.addOvalFilled(green, 15, 65, 70, 70) canvas.addOvalFilled(blue, 20, 70, 60, 60) canvas.addOvalFilled(makeColor(255, 0, 255), 25, 75, 50, 50) canvas.addOvalFilled(white, 30, 80, 40, 40) canvas.show() 17.24 Rewrite the mirror functions as methods in the MyPicture class.

Note: What mirror “functions” this question refers to are unclear, simply rewriting two of the mirror functions used in the book is sufficient. class MyPicture(Picture): def mirrorHorizontal(self): mirrorPoint = getHeight(self) / 2 height = getHeight(self) for x in range(0,getWidth(self)):

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for y in range(0,mirrorPoint): topPixel = getPixel(self ,x,y) bottomPixel = getPixel(self,x,height - y - 1) color = getColor(topPixel) setColor(bottomPixel ,color) def mirrorVertical(self): mirrorPoint = getWidth(self) / 2 width = getWidth(self) for y in range(0,getHeight(self)): for x in range(0,mirrorPoint): leftPixel = getPixel(self ,x,y) rightPixel = getPixel(self,width - x - 1,y) color = getColor(leftPixel) setColor(rightPixel ,color) 17.25 Make some modifications to Joe the Box. •Add a method to Box named setColor that takes a color as input, then makes the input color the new color for the box. (Maybe setDefaultColor should call setColor?) class Box: def __init__(self): self.setDefaultColor() self.size=10 self.position=(10,10) def setColor(self, color): self.color = color def setDefaultColor(self): self.setColor(red) •Add a method to Box named setSize that takes a number as input, then makes the input number the new size for the box. class Box: def setSize(self, size): self.size = size •Add a method to Box named setPosition that takes a list or tuple as a parameter, then makes that input the new position for the box. class Box: def setPosition(self, position): self.position = position

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• Change init so that it uses setSize and setPosition rather than simply setting the instance variables. class Box: def __init__(self): self.setDefaultColor() self.setSize(10) self.setPosition((10,10)) *17.26 Finish the Joe the Box example. (a) Implement grow and move. The method move takes as input a relative distance like (−10,15) to move 10 pixels left (x position) and 15 pixels down (y position).

Note: Grow is already implemented on the bottom of Chapter 17, Page 474 class Box: def move(self, x, y): xPos = self.position[0] yPos = self.position[1] xPos = xPos + x yPos = yPos + y self.position = (xPos, yPos) (b) Draw patterns by creating joe and jane, then move a little and draw, grow a little and draw, then repaint the new canvas. def makePattern(): jane = SadBox () joe = Box () canvas = makeEmptyPicture(300,300) canvas.show() for i in range(0, 30): jane.move(i, 0) joe.move(0,i) jane.draw(canvas) joe.draw(canvas) repaint(canvas) joe.grow(i) jane.grow(i) jane.draw(canvas) joe.draw(canvas) repaint(canvas)

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17.27 Create a movie with boxes growing and shrinking in it.

Note: The easiest solution to this problem is to simply have one box growing and one shrinking. One could instead change from shrinking to growing partway through, but this is not necessary. def boxesMovie(directory): jane = SadBox () joe = Box () jane.setSize(70) jane.setPosition((200,10)) for num in range (1 ,30): #29 frames canvas = makeEmptyPicture (300 ,250) numStr=str(num) joe.grow(2) jane.grow(-2) joe.draw(canvas) jane.draw(canvas) canvas.show() if num < 10: writePictureTo ( canvas , directory +"//frame0 "+ numStr +".jpg ") if num >= 10: writePictureTo ( canvas , directory +"//frame "+ numStr +".jpg ") movie = makeMovieFromInitialFile(directory+"//frame00.jpg"); return movie

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