A Concise Introduction to Programming in Python

208 Pages·2012·0.773 MB·English

by  Johnson, Mark J.

Computer Science A
Chapman & Hall/CRC
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Suitable for newcomers to computer science, A Concise Introduc- E
A CONCISE INTRODUCTION
tion to Programming in Python provides a succinct, yet complete, IN
first course in computer science using the Python programming lan- T
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The book features: U PYTHON
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• Short, modular chapters with brief and precise explanations, T
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intended for one class period O
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• Early introduction of basic procedural constructs such as
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functions, selection, and repetition, allowing them to be used O

throughout the course P
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• Objects are introduced in the middle of the course, and class O
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design comes toward the end
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• Examples, exercises, and projects from a wide range of
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application domains, including biology, physics, images, sound, M
mathematics, games, and textual analysis IN
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• No external libraries are required, simplifying the book’s use in

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common lab spaces N

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Each chapter introduces a main idea through a concrete example and Y
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a series of exercises. Designed to teach programming in a concise, H
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yet comprehensive way, this book provides a timely introduction for
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students and anyone interested in learning Python.
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K14279_Cover.indd 1 11/28/11 3:57 PM
A CONCISE INTRODUCTION
TO PROGRAMMING IN
PYTHON
CHAPMAN & HALL/CRC
TEXTBOOKS IN COMPUTING
Series Editors
John Impagliazzo Andrew McGettrick
Professor Emeritus, Hofstra University Department of Computer
and Information Sciences
University of Strathclyde
Aims and Scope

This series covers traditional areas of computing, as well as related technical areas, such as
software engineering, artificial intelligence, computer engineering, information systems, and
information technology. The series will accommodate textbooks for undergraduate and gradu-
ate students, generally adhering to worldwide curriculum standards from professional societ-
ies. The editors wish to encourage new and imaginative ideas and proposals, and are keen to
help and encourage new authors. The editors welcome proposals that: provide groundbreaking
and imaginative perspectives on aspects of computing; present topics in a new and exciting
context; open up opportunities for emerging areas, such as multi-media, security, and mobile
systems; capture new developments and applications in emerging fields of computing; and
address topics that provide support for computing, such as mathematics, statistics, life and
physical sciences, and business.
Published Titles

Pascal Hitzler, Markus Krötzsch, and Sebastian Rudolph,
Foundations of Semantic Web Technologies
Uvais Qidwai and C.H. Chen, Digital Image Processing: An Algorithmic
Approach with MATLAB®
Henrik Bærbak Christensen, Flexible, Reliable Software: Using Patterns
and Agile Development
John S. Conery, Explorations in Computing: An Introduction to
Computer Science
Lisa C. Kaczmarczyk, Computers and Society: Computing for Good
Mark J. Johnson, A Concise Introduction to Programming in Python
Chapman & Hall/CRC
TEXTBOOKS IN COMPUTING
A CONCISE INTRODUCTION
TO PROGRAMMING IN
PYTHON
Mark J. Johnson
CRC Press
Taylor & Francis Group
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© 2012 by Taylor & Francis Group, LLC
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Contents
Code Listings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Part I Foundations 1
1 Computer Systems and Software . . . . . . . . . . . . . . . . 3
2 Python Program Components . . . . . . . . . . . . . . . . . 7
3 Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4 Repetition: For Loops . . . . . . . . . . . . . . . . . . . . . . 19
5 Computer Memory: Integers . . . . . . . . . . . . . . . . . . 25
6 Selection: If Statements . . . . . . . . . . . . . . . . . . . . . 29
7 Algorithm Design and Debugging . . . . . . . . . . . . . . . 37
8 Repetition: While Loops . . . . . . . . . . . . . . . . . . . . 41
Project: Newton’s Method . . . . . . . . . . . . . . . . . . . 47
9 Computer Memory: Floats . . . . . . . . . . . . . . . . . . . 49
10 Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Project: Visualization . . . . . . . . . . . . . . . . . . . . . . 57
Part II Collections and Files 59
11 Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
12 Building Strings . . . . . . . . . . . . . . . . . . . . . . . . . 65
Project: ISBN Check Digits . . . . . . . . . . . . . . . . . . . 71
13 Computer Memory: Text . . . . . . . . . . . . . . . . . . . . 73
14 Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Project: Program Performance . . . . . . . . . . . . . . . . . 83
Project: Heat Diffusion . . . . . . . . . . . . . . . . . . . . . 85
15 Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
16 String Methods . . . . . . . . . . . . . . . . . . . . . . . . . 93
Project: File Compression . . . . . . . . . . . . . . . . . . . . 101
17 Mutable and Immutable Objects . . . . . . . . . . . . . . . . 103
Project: Hangman . . . . . . . . . . . . . . . . . . . . . . . . 107
18 Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Project: ELIZA . . . . . . . . . . . . . . . . . . . . . . . . . 115
Project: Shannon Entropy . . . . . . . . . . . . . . . . . . . 117
Project: Reading DNA Frames . . . . . . . . . . . . . . . . . 119
v
vi Contents
Part III Selected Topics 121
19 Sound Manipulation . . . . . . . . . . . . . . . . . . . . . . . 123
20 Sound Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . 129
21 Image Manipulation . . . . . . . . . . . . . . . . . . . . . . . 135
Project: Image Filters . . . . . . . . . . . . . . . . . . . . . . 143
22 Image Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . 147
23 Writing Classes . . . . . . . . . . . . . . . . . . . . . . . . . 153
24 Cooperating Classes . . . . . . . . . . . . . . . . . . . . . . . 159
Case Study: PPM Image Class . . . . . . . . . . . . . . . . . 165
25 Related Classes . . . . . . . . . . . . . . . . . . . . . . . . . 169
26 Functional Programming . . . . . . . . . . . . . . . . . . . . 175
27 Parallel Programming . . . . . . . . . . . . . . . . . . . . . . 181
28 Graphical User Interfaces . . . . . . . . . . . . . . . . . . . . 185
Bibliography 193
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Code Listings
1.1 Area of a Circle . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Mad Lib® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 Hypotenuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1 Harmonic Sum . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.1 Centipede . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.1 Prime Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . 41
8.2 Newton’s Method (Algorithm) . . . . . . . . . . . . . . . . . 47
10.1 Monte Carlo Integration . . . . . . . . . . . . . . . . . . . . . 52
11.1 Pig Latin Translation . . . . . . . . . . . . . . . . . . . . . . 61
12.1 DNA Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . 65
14.1 Sieve of Eratosthenes . . . . . . . . . . . . . . . . . . . . . . . 75
14.2 Heat Diffusion (Algorithm) . . . . . . . . . . . . . . . . . . . 85
15.1 Solve Jumble™ . . . . . . . . . . . . . . . . . . . . . . . . . . 87
16.1 GCS Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
18.1 Word Frequency . . . . . . . . . . . . . . . . . . . . . . . . . 109
19.1 Reverse WAV . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
20.1 Synthesizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
21.1 Two-Tone Image . . . . . . . . . . . . . . . . . . . . . . . . . 135
22.1 Mandelbrot Set . . . . . . . . . . . . . . . . . . . . . . . . . . 147
23.1 Sum of Dice . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
24.1 Chuck-a-Luck . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
24.2 Dice Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
24.3 ImagePPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
25.1 Sierpinski Triangle . . . . . . . . . . . . . . . . . . . . . . . . 169
26.1 Word Frequency (Functional Version) . . . . . . . . . . . . . 175
27.1 Monte Carlo Integration (Parallel Version) . . . . . . . . . . . 181
28.1 Chuck-a-Luck (GUI Version) . . . . . . . . . . . . . . . . . . 185
28.2 Dice GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
vii
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Preface
Welcome!
ThistextprovidesanintroductiontowritingsoftwareinPython.Noprevious
programming experience is necessary.
Most chapters begin with an example program illustrating a small set of new
concepts. These programs are available for download at http://www.central
.edu/go/conciseintro/. However, you might consider typing each program
in by hand rather than using the downloaded files. The reason is that you
can learn by typing, both in terms of thoroughly reading the programs, and
responding to error messages that result from typos. Rather than being a
hindrance, learning to deal with error messages will be quite helpful as you
write your own programs.
To Instructors
This text is designed for a first course in computer science and is suitable for
majors and non-majors. Among its features:
• Chapters are short, intended for one or at most two class periods. This
provides a flexible framework to build a course around.
• Explanations are brief and precise.
• Basic procedural constructs such as functions, selection, and repetition
areintroducedearly,allowingthemtobeusedthroughoutthesemester.
• Objects are (explicitly) used in the middle of the course, and writing
classes comes toward the end.
• Examples, exercises, and projects are from a wide range of application
domains,includingbiology,physics,images,sound,mathematics,games,
and textual analysis.
• Noexternallibrariesarerequired.Allexampleprogramsruninstandard
Python 3.
This text is designed to help teach programming rather than being an ency-
clopedic reference. Topics are introduced as needed for the examples, and the
focusisalwaysonwhatabeginningstudentmightneedtoknowatthatpoint.
ix