Python for kids : a playful introduction to programming

348 Pages·2013·13.557 MB·English

by  Briggs, Jason R

playPython_fullcvr_9.pdf 1 9/25/2013 5:46:14 PM
For kids aged 10+ (and their parents)
rReEaAlL pPrrooggrraammmmiinngg.. PP YY TT HH OO NN
rReEaALl eEaAsSyY..
PP
Illustrations by Miran Lipovaca YY
F O R K I D S
F O R K I D S
Python is a powerful, expressive program- As you strike out on your programming TT
ming language that’s easy to learn and fun to adventure, you’ll learn how to:
HH
use! But books about learning to program in
 Use fundamental data structures like lists,
Python can be kind of dull, gray, and boring,
tuples, and maps
OO
and that’s no fun for anyone. A Playful Introduction to Programming
 Organize and reuse your code with func-
Python for Kids brings Python to life and
brings you (and your parents) into the world of tions and modules NN
programming. The ever-patient Jason R. Briggs  Use control structures like loops and
will guide you through the basics as you experi- conditional statements J a s o n R . B r i g g s
ment with unique (and often hilarious) example  Draw shapes and patterns with Python’s FF
C
programs that feature ravenous monsters, secret turtle module
M OO
agents, thieving ravens, and more. New terms
 Create games, animations, and other
Y
are defined; code is colored, dissected, and
graphical wonders with tkinter
CM RR
explained; and quirky, full-color illustrations
Why should serious adults have all the fun?
MY
keep things on the lighter side.
Python for Kids is your ticket into the amaz-
CY Chapters end with programming puzzles
CMY designed to stretch your brain and strengthen ing world of computer programming. KK
K your understanding. By the end of the book ABOUT THE AUTHOR
II
you’ll have programmed two complete games:
Jason R. Briggs has been a programmer since DD
a clone of the famous Pong and “Mr. Stick Man
the age of eight, when he first learned BASIC on
Races for the Exit”—a platform game with
a Radio Shack TRS-80. He has written software SS
jumps, animation, and much more.
professionally as a developer and systems archi-
tect and served as Contributing Editor for Java
Python runs on Windows, Developer’s Journal. His articles have appeared
OS X, Linux, OLPC Laptops, in JavaWorld, ONJava, and ONLamp. Python
and even Raspberry pi!
for Kids is his first book.
B
r
i
$34.95 ($36.95 CDN) PROGRAMSHELVE IN gg
MIN: s
G LAN
G
UAG
wwTwH.En oFsINtaErScTh .IcNom ES/PYTH
GEEK ENTERTAINMENT™ ON

Praise for
Python for Kids
“Jason Briggs manages to successfully describe programming
to kids without sounding like he’s dumbing down the content.
The lessons are well-constructed and leave the reader with a
feeling of accomplishment in each chapter.”
—Marziah Karch, Wired.com
“An excellent introduction to programming for anyone interested
in learning to program, regardless of their age. The material is
extremely well organized and presented, and makes for a great
resource for either home or school.”
—Roy Wood, GeekDad
“This book offers a good introduction to computer programming.
. . . An excellent family bonding experience.”
—Patrice Gans, Education Week
“By the end of the book, you have a fully-functional platform
game running, and most likely a head full of ideas about your
next game. Python for Kids is just as good an introduction for
adults learning to code.”
—Matthew Humphries, Geek.com
“Easy to read, provides sound programming advice and very
clear explanations of how programming languages work. A
great book for anyone who wants to break into programming
without pangs of inadequacy.”
—Sandra Henry-Stocker, ITworld
pfk_TITLE_COPY.indd 1 9/26/2013 4:50:51 PM

P y t h o n
fo r   K i d s
A Playful Introduction
to Programming
By Jason R. Briggs
San Francisco
PYTHON FOR KIDS. Copyright © 2013 by Jason R. Briggs.
All rights reserved. No part of this work may be reproduced or transmitted in any form or by any
means, electronic or mechanical, including photocopying, recording, or by any information storage
or retrieval system, without the prior written permission of the copyright owner and the publisher.
Printed in Korea
Fourth printing
16 15 14 13 4 5 6 7 8 9
ISBN-10: 1-59327-407-6
ISBN-13: 978-1-59327-407-8
Publisher: William Pollock
Production Editor: Serena Yang
Cover and Interior Design: Octopod Studios
Illustrator: Miran Lipovaca
Developmental Editor: William Pollock
Technical Reviewers: Josh Pollock and Maria Fernandez
Copyeditor: Marilyn Smith
Compositor: Serena Yang
Proofreader: Greg Teague
For information on distribution, translations, or bulk sales, please contact No Starch Press, Inc. directly:
No Starch Press, Inc.
245 8th Street, San Francisco, CA 94103
phone: [phone]; fax: [phone]; [e-mail]; http://www.nostarch.com/
Library of Congress Cataloging-in-Publication Data
Briggs, Jason R.
Python for kids : a playful introduction to programming / by Jason R. Briggs.
pages cm
Audience: 10+
Includes index.
ISBN 978-1-59327-407-8 -- ISBN 1-59327-407-6
1. Computer software--Juvenile literature. 2. Computer programming--Juvenile literature. 3.
Python (Computer program language)--Juvenile literature. I. Title.
QA76.52.B75 2013
005.13'3--dc23
2012044047
No Starch Press and the No Starch Press logo are registered trademarks of No Starch Press, Inc.
Other product and company names mentioned herein may be the trademarks of their respective
owners. Rather than use a trademark symbol with every occurrence of a trademarked name, we
are using the names only in an editorial fashion and to the benefit of the trademark owner, with
no intention of infringement of the trademark.
The information in this book is distributed on an “As Is” basis, without warranty. While every
precaution has been taken in the preparation of this work, neither the author nor No Starch Press,
Inc. shall have any liability to any person or entity with respect to any loss or damage caused or
alleged to be caused directly or indirectly by the information contained in it.
Production Date: September 26, 2013
Plant & Location: Printed by We SP, South Korea
Job / Batch #: 072313
pfk_TITLE_COPY.indd 4 9/25/2013 5:30:07 PM
BRIef Contents
About the Author, Illustrator, and Technical Reviewers. . . . . . . . . . . . . . . xv
Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xvii
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Part I: Learning to Program
Chapter 1: Not All Snakes Slither. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Chapter 2: Calculations and Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Chapter 3: Strings, Lists, Tuples, and Maps. . . . . . . . . . . . . . . . . . . . . . . . .25
Chapter 4: Drawing with Turtles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Chapter 5: Asking Questions with if and else. . . . . . . . . . . . . . . . . . . . . . . .53
Chapter 6: Going Loopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
Chapter 7: Recycling Your Code with Functions and Modules . . . . . . . . . .81
Chapter 8: How to Use Classes and Objects . . . . . . . . . . . . . . . . . . . . . . . . .93
Chapter 9: Python’s Built-in Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . .109
Chapter 10: Useful Python Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
Chapter 11: More Turtle Graphics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145
Chapter 12: Using tkinter for Better Graphics. . . . . . . . . . . . . . . . . . . . . .163
Part II: Bounce!
Chapter 13: Beginning Your First Game: Bounce!. . . . . . . . . . . . . . . . . . .193
Chapter 14: Finishing Your First Game: Bounce! . . . . . . . . . . . . . . . . . . .205
Part III : Mr. stick Man Races for the exit
Chapter 15: Creating Graphics for the Mr. Stick Man Game . . . . . . . . . .221
Chapter 16: Developing the Mr. Stick Man Game . . . . . . . . . . . . . . . . . . .233
Chapter 17: Creating Mr. Stick Man. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251
Chapter 18: Completing the Mr. Stick Man Game. . . . . . . . . . . . . . . . . . .259
Afterword: Where to Go from Here . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .285
Appendix: Python Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .293
Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .307
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313

Contents In DetAIL
About the Author, Illustrator, and
technical Reviewers xv
Acknowledgments xvii
Introduction xix
Why Python?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xx
How to Learn to Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xx
Who Should Read This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
What’s in This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxii
The Companion Website. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii
Have Fun! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii
Part I: Learning to Program
1
not All snakes slither 3
A Few Words About Language. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Installing Python . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Installing Python on Windows 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Installing Python on Mac OS X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Installing Python on Ubuntu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Once You’ve Installed Python . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Saving Your Python Programs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
What You Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
2
Calculations and Variables 15
Calculating with Python. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Python Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
The Order of Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Variables Are Like Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Using Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
What You Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
3
strings, Lists, tuples, and Maps 25
Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Creating Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Handling Problems with Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Embedding Values in Strings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Multiplying Strings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Lists Are More Powerful Than Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Adding Items to a List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Removing Items from a List. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
List Arithmetic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Tuples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Python Maps Won’t Help You Find Your Way . . . . . . . . . . . . . . . . . . . . . . .39
What You Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
Programming Puzzles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
#1: Favorites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
#2: Counting Combatants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
#3: Greetings! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
4
Drawing with turtles 43
Using Python’s turtle Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
Creating a Canvas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
Moving the Turtle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
What You Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
Programming Puzzles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
#1: A Rectangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
#2: A Triangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
#3: A Box Without Corners. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
5
Asking Questions with if and else 53
if Statements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
A Block Is a Group of Programming Statements . . . . . . . . . . . . . . .54
Conditions Help Us Compare Things. . . . . . . . . . . . . . . . . . . . . . . . .57
if-then-else Statements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
if and elif Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
Combining Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Variables with No Value—None . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
The Difference Between Strings and Numbers. . . . . . . . . . . . . . . . . . . . . . .62
What You Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
viii Contents in Detail