Python Crash Course Python Crash Course. Copyright © 2016 by Eric Matthes. 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. First printing 19 18 17 16 15 1 2 3 4 5 6 7 8 9 ISBN-10: 1-59327-603-6 ISBN-13: 978-1-59327-603-4 Publisher: William Pollock Production Editor: Riley Hoffman Cover Illustration: Josh Ellingson Interior Design: Octopod Studios Developmental Editors: William Pollock, Liz Chadwick, and Leslie Shen Technical Reviewer: Kenneth Love Copyeditor: Anne Marie Walker Compositor: Riley Hoffman Proofreader: James Fraleigh 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: 415.863.9900; [email protected] www.nostarch.com Library of Congress Cataloging-in-Publication Data Matthes, Eric, 1972- Python crash course : a hands-on, project-based introduction to programming / by Eric Matthes. pages cm Includes index. Summary: "A project-based introduction to programming in Python, with exercises. Covers general programming concepts, Python fundamentals, and problem solving. Includes three projects - how to create a simple video game, use data visualization techniques to make graphs and charts, and build an interactive web application"-- Provided by publisher. ISBN 978-1-59327-603-4 -- ISBN 1-59327-603-6 1. Python (Computer program language) I. Title. QA76.73.P98M38 2015 005.13'3--dc23 2015018135 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. about the author Eric Matthes is a high school science and math teacher living in Alaska, where he teaches an introductory Python course. He has been writing programs since he was five years old. Eric currently focuses on writing soft- ware that addresses inefficiencies in education and brings the benefits of open source software to the field of education. In his spare time he enjoys climbing mountains and spending time with his family. about the technical reviewer Kenneth Love has been a Python programmer and teacher for many years. He has given talks and tutorials at conferences, done professional train- ings, been a Python and Django freelancer, and now teaches for an online education company. Kenneth is also the co-creator of the django-braces package, which provides several handy mixins for Django’s class-based views. You can keep up with him on Twitter at @kennethlove. For my father, who always made time to answer my questions about programming, and for Ever, who is just beginning to ask me his questions BrIe f Contents Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxvii Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxix Part I: BasICs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Chapter 1: Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Chapter 2: Variables and Simple Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Chapter 3: Introducing Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37 Chapter 4: Working with Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Chapter 5: if Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75 Chapter 6: Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95 Chapter 7: User Input and while Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117 Chapter 8: Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133 Chapter 9: Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161 Chapter 10: Files and Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .189 Chapter 11: Testing Your Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .215 Part II: ProjeCts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 Project 1: Alien Invasion Chapter 12: A Ship That Fires Bullets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .235 Chapter 13: Aliens! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .265 Chapter 14: Scoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .291