How to Think Like a
(Python) Programmer

Allen B. Downey

Version 0.9.2

• Preface
• The strange history of this book
• For the teacher
• For the student
• Contributor List
• The way of the program
• The Python programming language
• What is a program?
• What is debugging?
• Formal and natural languages
• The first program
• Debugging
• Glossary
• Exercises
• Variables, expressions and statements
• Values and types
• Variables
• Variable names and keywords
• Statements
• Operators and operands
• Expressions
• Order of operations
• String operations
• Comments
• Debugging
• Glossary
• Exercises
• Functions
• Function calls
• Type conversion functions
• Math functions
• Composition
• Adding new functions
• Definitions and uses
• Flow of execution
• Parameters and arguments
• Variables and parameters are local
• Stack diagrams
• Fruitful functions and void functions
• Why functions?
• Debugging
• Glossary
• Exercises
• Case study: interface design
• TurtleWorld
• Simple repetition
• Exercises
• Encapsulation
• Generalization
• Interface design
• Refactoring
• A development plan
• docstring
• Glossary
• Exercises
• Conditionals and recursion
• Modulus operator
• Boolean expressions
• Logical operators
• Conditional execution
• Alternative execution
• Chained conditionals
• Nested conditionals
• Recursion
• Stack diagrams for recursive functions
• Infinite recursion
• Keyboard input
• Debugging
• Glossary
• Exercises
• Fruitful functions
• Return values
• Incremental development
• Composition
• Boolean functions
• More recursion
• Leap of faith
• One more example
• Checking types
• Debugging
• Glossary
• Iteration
• Multiple assignment
• Updating variables
• The while statement
• break
• Square roots
• Algorithms
• Debugging
• Glossary
• Exercises
• Strings
• A string is a sequence
• len
• Traversal with a for loop
• String slices
• Strings are immutable
• A find function
• Looping and counting
• string methods
• The in operator
• String comparison
• Debugging
• Glossary
• Case study: word play
• Reading word lists
• Exercises
• Search
• Looping with indices
• Glossary
• Lists
• A list is a sequence
• Lists are mutable
• Traversing a list
• List operations
• List slices
• List methods
• Map, filter and reduce
• Deleting elements
• Objects and values
• Aliasing
• List arguments
• Copying lists
• Lists and strings
• Debugging
• Glossary
• Exercises
• Dictionaries
• Dictionary as a set of counters
• Looping and dictionaries
• Reverse lookup
• Dictionaries and lists
• Hints
• Long integers
• Glossary
• Exercises
• Tuples
• Tuples are immutable
• Tuple assignment
• Tuples as return values
• Lists and tuples
• Dictionaries and tuples
• Sorting tuples
• Sequences of sequences
• Debugging
• Glossary
• Exercises
• Case study: data structure selection
• DSU
• Word frequency analysis
• Random numbers
• Word histogram
• Most common words
• Optional arguments
• Dictionary subtraction
• Random words
• Markov analysis
• Data structures
• Debugging
• Glossary
• Files
• Persistence
• Reading and writing
• Format operator
• Filenames and paths
• Catching exceptions
• Databases
• Pickling
• Debugging
• Glossary
• Classes and objects
• User-defined types
• Attributes
• Rectangles
• Instances as return values
• Objects are mutable
• Copying
• Debugging
• Glossary
• Exercises
• Classes and functions
• Time
• Pure functions
• Modifiers
• Prototyping versus planning
• Debugging
• Glossary
• Exercises
• Classes and methods
• Object-oriented features
• print_time
• Another example
• A more complicated example
• The init method
• The str method
• Operator overloading
• Type-based dispatch
• Polymorphism
• Debugging
• Glossary
• Inheritance
• Card objects
• Class attributes
• Comparing cards
• Decks
• Printing the deck
• Add, remove, shuffle and sort
• Inheritance
• Writing modules for import
• Class diagrams
• Glossary
• Exercises
• Case study: Tkinter
• Widgets
• Buttons and callbacks
• Canvas widgets
• Coordinate sequences
• More widgets
• Packing widgets
• Menus and Callables
• Binding
• Debugging
• Glossary
• Exercises
• Index