1 The Way of the Program 1
1.1 The Python Programming Language 1
1.2 What Is a Program? 3
1.3 What Is Debugging? 3
1.3.1 Syntax Errors 3
1.3.2 Runtime Errors 4
1.3.3 Semantic Errors 4
1.3.4 Experimental Debugging 4
1.4 Formal and Natural Languages 5
1.5 The First Program 6
1.6 Debugging 7
1.7 Glossary 8
1.8 Exercises 9
2 Variables, Expressions, and Statements 10
2.1 Values and Types 10
2.2 Variables 11
2.3 Variable Names and Keywords 13
2.4 Statements 13
2.5 Operators and Operands 14
2.6 Expressions 15
2.7 Order of Operations 15
2.8 String Operations 16
2.9 Comments 17
2.10 Debugging 17
2.11 Glossary 18
2.12 Exercises 19
3 Functions 21
3.1 Function Calls 21
3.2 Type Conversion Functions 21
3.3 Math Functions 22
3.4 Composition 23
3.5 Adding New Functions 24
3.6 Definitions and Uses 26
3.7 Flow of Execution 26
3.8 Parameters and Arguments 27
3.9 Variables and Parameters Are Local 28
3.10 Stack Diagrams 29
3.11 Fruitful Functions and Void Functions 30
3.12 Why Functions? 31
3.13 Debugging 31
3.14 Glossary 32
3.15 Exercises 33
4 Case Study: Interface Design 35
4.1 Turtle World 35
4.2 Simple Repetition 36
4.3 Exercises 37
4.4 Encapsulation 38
4.5 Generalization 39
4.6 Interface Design 40
4.7 Refactoring 41
4.8 A Development Plan 42
4.9 Docstring 43
4.10 Debugging 43
4.11 Glossary 44
4.12 Exercises 44
5 Conditionals and Recursion 46
5.1 Modulus Operator 46
5.2 Boolean Expressions 46
5.3 Logical Operators 47
5.4 Conditional Execution 48
5.5 Alternative Execution 48
5.6 Chained Conditionals 49
5.7 Nested Conditionals 49
5.8 Recursion 50
5.9 Stack Diagrams for Recursive Functions 52
5.10 Infinite Recursion 52
5.11 Keyboard Input 53
5.12 Debugging 54
5.13 Glossary 55
5.14 Exercises 56
6 Fruitful Functions 59
6.1 Return Values 59
6.2 Incremental Development 60
6.3 Composition 63
6.4 Boolean Functions 64
6.5 More Recursion 65
6.6 Leap of Faith 67
6.7 One More Example 67
6.8 Checking Types 68
6.9 Debugging 69
6.10 Glossary 70
6.11 Exercises 71
7 Iteration 73
7.1 Multiple Assignment 73
7.2 Updating Variables 74
7.3 The while Statement 75
7.4 break 76
7.5 Square Roots 77
7.6 Algorithms 79
7.7 Debugging 79
7.8 Glossary 80
7.9 Exercises 80
8 Strings 82
8.1 A String Is a Sequence 82
8.2 len 83
8.3 Traversal with a for Loop 83
8.4 String Slices 85
8.5 Strings Are Immutable 86
8.6 Searching 86
8.7 Looping and Counting 87
8.8 string Methods 87
8.9 The in Operator 89
8.10 String Comparison 89
8.11 Debugging 90
8.12 Glossary 92
8.13 Exercises 92
9 Case Study: Word Play 95
9.1 Reading Word Lists 95
9.2 Exercises 96
9.3 Search 97
9.4 Looping with Indices 99
9.5 Debugging 100
9.6 Glossary 101
9.7 Exercises 101
10 Lists 103
10.1 A List Is a Sequence 103
10.2 Lists Are Mutable 104
10.3 Traversing a List 105
10.4 List Operations 106
10.5 List Slices 106
10.6 List Methods 107
10.7 Map, Filter, and Reduce 108
10.8 Deleting Elements 109
10.9 Lists and Strings 110
10.10 Objects and Values 111
10.11 Aliasing 113
10.12 List Arguments 113
10.13 Debugging 115
10.14 Glossary 116
10.15 Exercises 117
11 Dictionaries 119
11.1 Dictionary as a Set of Counters 121
11.2 Looping and Dictionaries 123
11.3 Reverse Lookup 123
11.4 Dictionaries and Lists 124
11.5 Memos 126
11.6 Global Variables 128
11.7 Long Integers 129
11.8 Debugging 130
11.9 Glossary 131
11.10 Exercises 131
12 Tuples 133
12.1 Tuples Are Immutable 133
12.2 Tuple Assignment 135
12.3 Tuples as Return Values 136
12.4 Variable-Length Argument Tuples 136
12.5 Lists and Tuples 138
12.6 Dictionaries and Tuples 139
12.7 Comparing Tuples 141
12.8 Sequences of Sequences 142
12.9 Debugging 143
12.10 Glossary 144
12.11 Exercises 145
13 Case Study: Data Structure Selection 147
13.1 Word Frequency Analysis 147
13.2 Random Numbers 148
13.3 Word Histogram 149
13.4 Most Common Words 151
13.5 Optional Parameters 152
13.6 Dictionary Subtraction 152
13.7 Random Words 153
13.8 Markov Analysis 154
13.9 Data Structures 155
13.10 Debugging 157
13.11 Glossary 158
13.12 Exercises 158
14 Files 159
14.1 Persistence 159
14.2 Reading and Writing 159
14.3 Format Operator 160
14.4 Filenames and Paths 161
14.5 Catching Exceptions 163
14.6 Databases 164
14.7 Pickling 165
14.8 Pipes 166
14.9 Writing Modules 167
14.10 Debugging 168
14.11 Glossary 169
14.12 Exercises 169
15 Classes and Objects 172
15.1 User-Defined Types 172
15.2 Attributes 173
15.3 Rectangles 174
15.4 Instances as Return Values 176
15.5 Objects Are Mutable 176
15.6 Copying 177
15.7 Debugging 179
15.8 Glossary 179
15.9 Exercises 180
16 Classes and Functions 182
16.1 Time 182
16.2 Pure Functions 183
16.3 Modifiers 184
16.4 Prototyping versus Planning 185
16.5 Debugging 187
16.6 Glossary 188
16.7 Exercises 188
17 Classes and Methods 189
17.1 Object-Oriented Features 189
17.2 Printing Objects 190
17.3 Another Example 192
17.4 A More Complicated Example 192
17.5 The Init Method 193
17.6 The__str__ method 194
17.7 Operator Overloading 195
17.8 Type-Based Dispatch 195
17.9 Polymorphism 197
17.10 Debugging 198
17.11 Glossary 199
17.12 Exercises 199
18 Inheritance 201
18.1 Card Objects 201
18.2 Class Attributes 202
18.3 Comparing Cards 204
18.4 Decks 205
18.5 Printing the Deck 205
18.6 Add, Remove, Shuffle, and Sort 206
18.7 Inheritance 207
18.8 Class Diagrams 209
18.9 Debugging 210
18.10 Glossary 211
18.11 Exercises 212
19 Case Study: Tkinter 214
19.1 GUI 214
19.2 Buttons and Callbacks 215
19.3 Canvas Widgets 216
19.4 Coordinate Sequences 217
19.5 More Widgets 218
19.6 Packing Widgets 220
19.7 Menus and Callables 223
19.8 Binding 223
19.9 Debugging 226
19.10 Glossary 227
19.11 Exercises 228
Appendix 231
Index 241