Table of Contents

[CHAPTER] 1 j INTRODUCTION 1

1.1 | Two Fundamental Ideas ofComputer Science: Algorithms and Information

| Processing 2

I 1,1.1 | Algorithms 2

| 1,1.2 I Information Processing 4

1.1 | Exercises 5

1.2 I The Structure of a Modern Computer System 6

| 1.2.1 '. Computer Hardware 6

j 1.2.2 < Computer Software 8

1.2 | Exercises,.. -10

1.3 I A Not-So-BriefHistory of Computing Systems ..10*

1.3.1 Before Electronic Digital Computers 11

J 1.3.2 i The First Electronic Digital Computers (1940-1950) 15

| 1.3.3 ; The First Programming Languages (1950-1965) 16

1 1.3.4 Integrated Circuits, Interaction, and Timesharing (1965-1975) 18

j 1.3.5 j Personal Computing and Networks (1975-1990) 19

ti 1.3.6 ,' Consultation, Communication, and Ubiquitous ComputingI ; (1990-Present) 21

1.4 I Getting Started with Python Programming 23

J 1.4.1 { Running Code in the Interactive Shell 23

J 1.4.2 : Input, Processing, and Output 25

| 1.4.3 Editing, Saving, and Running a Script 28

I 1,4.4 ; Behind the Scenes: How Python Works 29

1.4 j Exercises... 30

1.5 i Detecting and Correcting Syntax Errors , 31

1.5 Exercises 32

I Suggestions for Further Reading 32

I Summary 33

I Review Questions 35

I Projects 37

[CHAPTER] 2 * SOFTWARE DEVELOPMENT, DATA TYPES, AND

{ EXPRESSIONS 39

2.1 | The Software Development Process 40

2.1 | Exercises 43

2.2 I Case Study: Income 'lax Calculator 43

I 2.2.1 Request 43

| 2.2.2 Analysis 44

f 2.2.3, Design 44

2.2.4 ;: Implementation (Coding) 45v 2.2.5 Testing 46

2.3 § Strings, Assignment, and Comments 47

1 2.3.1 I Data Types 47

I 2.3.2 | String Literals 48

| 2.3.3 | Escape Sequences 50

| 2.3.4 | String Concatenation 50

| 2.3.5 j Variables and the Assignment Statement 51

I 2.3.6 S Program Comments and Docstrings 52

2.3 j Exercises 53

2.4 | Numeric Data Types and Character Sets 54

I 2.4.1 | Integers 54I 2.4.2 | Floating-Point Numbers 55

I 2.4.3 1 Character Sets 55

2.4 1 Exercises 572.5 j Expressions 58

I 2.5.1 | Arithmetic Expressions 58

I 2.5.2 1 Mixed-Mode Arithmetic and Type Conversions 60

2.5 | Exercises 63

2.6 I Using Functions and Modules 63

j 2.6.1 j Calling Functions: Arguments and Return Values 64

j 2.6.2 j The math Module 65

I 2.6.3 I The Main Module 66

j 2.6.4 | Program Format and Structure 67

I 2.6.5 | Running a Script from a Terminal Command Prompt 68

2.6 jj Exercises 70

| Summary 70

| Review Questions 72

| Projects 73

[CHAPTER] 3 !; CONTROL STATEMENTS 75

3.1 j Definite Iteration: The for Loop 76

I 3.1.1 1 Executing a Statement a Given Number ofTimes 76I 3.1.2 I Count-Controlled Loops 77I 3.1.3 j Augmented Assignment 79

I 3.1.4 | Loop Errors: Off-by-One Error 80

I 3.1.5 | Traversing the Contents of a Data Sequence 80

I 3.1.6 I Specifying the Steps in the Range 81

| 3.1.7 I Loops That Count Down 82

3.1 | Exercises 83

3.2 I FormattingText for Output 83

3.2 I Exercises 86

3.3 I Case Study: An Investment Report 873 3.3.1 f Request 87

| 3.3-2 Analysis 87

| 3.3.3 j Design 88

S 3.3.4 | Implementation (Coding) 88I 3.3.5 | Testing 90

3.4 i Selection: if and if-else Statements 91

1 3.4.1 | The Boolean Type, Comparisons, and Boolean Expressions 91

1 3.4.2 1 if-else Statements 92

I 3.4.3 I One-Way Selection Statements 94

| 3.4.4 | Multi-way if Statements 95

| 3.4.5 ; Logical Operators and Compound Boolean Expressions 97

3.4.6 5 Short-Circuit Evaluation 99

3.4.7 ; Testing Selection Statements 100

3.4 | Exercises •101

3.5 | Conditional Iteration: The while Loop 102

j 3.5.1 « The Structure and Behavior of a while Loop 102

3.5.2;

Count Control with a while Loop 104

| 3.5.3 i The while True Loop and the break Statement 105

| 3.5.4 1 Random Numbers 107

| 3.5.5 ,! Loop Logic, Errors, and Testing 109

3.5 Exercises 109

3.6 | Case Study: Approximating Square Roots 110

I 3.6.1 1 Request 110

1 3.6.2 f Analysis 110

J 3.6.3 | Design 110

| 3.6.4 I Implementation (Coding) 112

I 3.6.5 ! Testing 113

£ Summary 113

| Review Questions 116

Projects 118

[CHAPTER] 4 STRINGS AND TEXT FILES 121

4.1 J Accessing Characters and Substrings in Strings 122

| 4.1.1 | The Structure of Strings 122

| 4.1.2 | The Subscript Operator 123

| 4.1.3 }< Slicing for Substrings 124

| 4.1.4 1 Testing for a Substring with the in Operator 125

4.1 1 Exercises 126

4.2 1 Data Encryption 126

4.2 J Exercises 129

4.3 | Strings and Number Systems 129

| 4.3.1 ; The Positional System for Representing Numbers 130

| 4.3.2 J Converting Binary to Decimal 131

| 4.3.3 | Converting Decimal to Binary 132

| 4.3.4 | Conversion Shortcuts 133

| 4.3.5 1 Octal and Hexadecimal Numbers 134

4.3 | Exercises 136

4.4 | StringMethods 136

4.4 | Exercises 140

4.5 J Text Files 141

1 4.5.1 I Text Files and Their Format 141

| 4.5.2 j Writing Text to a File 142

3 4.5.3 } Writing Numbers to a File 142

I 4.5,4 j Reading Text from a File 143

I 4.5.5 | ReadingNumbers from a File 145

| 4.5.6 1 Accessing and Manipulating Files and Directories on Disk 146

[CHAPTER] 5

4.5 §j Exercises 148

4.6 % Case Study: Text Analysis 148

1 4.6.1 } Request 149

1 4.6.2 | Analysis 149

| 4.6.3 t Design 1501 4.6.4 5 Implementation (Coding) 151

| 4.6.5 I Testing 152

| Summary 153

'% Review Questions •154

| Projects 156

LISTS AND DICTIONARIES 159

5.1 | Lists 160

I 5.1.1 jj List Literals and Basic Operators 160

| 5.1.2 j Replacing an Element in a List 163

1 5.1.3 | List Methods for Inserting and Removing Elements 165

I 5.1.4 f Searching a List 167

I 5.1.5 j Sorting a List 168

| 5.1.6 ! Mutator Methods and the Value None 168

| 5.1.7 j Aliasing and Side Effects 169

| 5.1.8 | Equality: Object Identity and Structural Equivalence 171

1 5.1.9 \ Example: Using a List to Find the Median of a Set of Numbers 172

1 5.1.10 | Tuples 173

Exercises 174

Defining Simple Functions 1755.2.1 \ The Syntax of Simple Function Definitions 175

5.2.2 ] Parameters and Arguments 176

5.2.3 | The return Statement 1775.2.4 | Boolean Functions 177

5.2.5 > Defining a main Function 178

Exercises 179Case Study: Generating Sentences 1795.3.1 I Request 179

5.3.2 I Analysis 1795.3.3 | Design 180

5.3.4 | Implementation (Coding) 182

5.3.5 | Testing 183

Dictionaries 183

| 5.4.1 j Dictionary Literals 183

| 5.4.2 | Adding Keys and Replacing Values 184

I 5.4.3 1 Accessing Values 185

| 5.4.4 1 Removing Keys 186

| 5.4.5 I Traversing a Dictionary 186

I 5.4.6| Example: The Hexadecimal System Revisited 188

| 5.4.7 S Example: Finding the Mode of a List ofValues 189

5.4 I Exercises 190

5.1

5.2

5.2

5.3

5.4

5.5 I Case Study: Nondirective Psychotherapy 191I 5.5.1 1 Request 191I 5.5.2 \ Analysis 191

§ 5.5.3 \ Design 1921 5.5.4 'i Implementation (Coding) 193I 5.5.5 I Testing 195

| Summary 195j Review Questions 196| Projects 198

[CHAPTER] 6 j DESIGN WITH FUNCTIONS 201

6.1 | Functions as Abstraction Mechanisms, 202

j 6.1.1 I Functions Eliminate Redundancy 2021 6.1.2 j Functions Hide Complexity 203

I 6.1.3 | Functions Support General Methods with Systematic Variations 2041 6.1.4 t Functions Support die Division of Labor 205

6.1 Exercises205

6.2 I Problem Solving with Top-Down Design 206| 6.2.1 I The Design ofthe Text-Analysis Program 2061 6.2.2 I The Design of the Sentence-Generator Program 207I 6.2.3 I The Design of the Doctor Program 209

6.2 I Exercises210

6.3 1 Design with Recursive Functions 211I 6.3.1 | Defining a Recursive Function 211I 6.3.2 I Tracing a Recursive Function 213

I 6.3.3 | Using Recursive Definitions to Construct Recursive Functions .......214I 6.3.4 I Recursion in Sentence Structure ..214J 6.3.5 j Infinite Recursion 215

| 6.3.6 ! The Costs and Benefits of Recursion 2166.3 | Exercises 2186.4 J Case Study: Gathering Information from a File System 219

I 6.4.1 ! Request 219I 6.4.2 J Analysis 220| 6.4.3 | Design 222

| 6.4.4 j Implementation (Coding) 2246.5 | Managing a Program's Namespace 227

| 6.5.1 | Module Variables, Parameters, and temporary Variables 227I 6.5.2 | Scope 228

6.5.3 | Lifetime 229I 6.5.4 i Default (Keyword) Arguments 230

6.5 I Exercises 2326.6 | Higher-Order Functions (Advanced Topic) 233

| 6.6.1 I Functions as First-Class Data Objects 2336.6.2

'

Mapping 2346.6.3 \ Filtering 2366.6.4 I Reducing 2376.6.5 f| Using lambda to Create Anonymous Functions 2376.6.6 I Creating Jump Tables 238

6.6

[CHAPTER] 77.1

7.1

7.2

7.3

7.3

[CHAPTER] 88.1

Exercises 239

Summary 240

Review Questions 242

Projects 244

SIMPLE GRAPHICS AND IMAGE PROCESSING 247

Simple Graphics 248

7.1.1 ;! Overview ofTurtle Graphics 24871.2 Turtle Operations 249

71.3 | Object Instantiation and the turtle Module 252

7.1.4 s Drawing Two-Dimensional Shapes 25471.5 I Taking a Random Walk 25571.6 5 Colors and the RGB System 256

71.7 | Example: Drawing with Random Colors 25771.8 j Examining an Object's Attributes 259

7.1.9 j Manipulating a Turtle's Screen 259

7.1.10 I Setting up a cfg File and Running IDLE 260

Exercises 261

Case Study: Recursive Patterns in Fractals 262

72.1 | Request 263

72.2 I Analysis 263

72.3 i Design 264

7.2.4 ! Implementation (Coding) 266

Image Processing 26773.1 I Analog and Digital Information 2677.3.2 Sampling and Digitizing Images 268

73.3 I Image File Formats 26873.4 | Image-Manipulation Operations 269

7.3.5 • The Properties ofImages 270

73.6 | The images Module 27073.7 s A Loop Pattern for Traversing a Grid 274

73.8 | A Word on Tuples 275

73.9 | Converting an Image to Black and White 2767.3.10 I Converting an Image to Grayscale 278

73.11 j Copying an Image 279

7.3.12 : Blurring an Image 280

73.13 | Edge Detection 2817.3.14 1 Reducing the Image Size 282

Exercises 284

Summary••• 285

Review Questions 286

Projects 288

DESIGN WITH CLASSES 293

Getting Inside Objects and Classes 2948.1.1 i A First Example: The Student Class 295

8.1.2 i Docstrings 298

8.1.3 1 Method Definitions 298

f 8.1.4 \ The init Method and Instance Variables 2998.1.5 i The _str_ Method 3008.1.6 \ Accessors and Mutators 300

| 8.1.7 : The Lifetime of Objects 301

| 8.1.8 < Rules ofThumb for Defining a Simple Class 3028.1 | Exercises 3038.2 I Case Study: Playing the Game ofCraps 303

I 8.2.1 Request 303I 8.2.2 "'

Analysis 303| 8.2.3 ; Design 304I 8.2.4 ', Implementation (Coding) 306

8.3 I Data-Modeling Examples 309

| 8.3.1 f Rational Numbers 309I 8.3.2 l Rational Number Arithmetic and Operator Overloading 311

| 8.3.3 ! Comparison Methods 312

j| 8.3.4 | Equality and die eq Method..... 314I 8.3.5 * Savings Accounts and Class Variables 315| 8.3.6 J Putting the Accounts into a Bank 317S 8,3.7 \ Using pickle for Permanent Storage of Objects 319| 8.3.8 I Input of Objects and the try-except Statement 320

I 8.3.9 i Playing Cards 3218.3 I Exercises 3258.4 | Case Study: An ATM 325

I 8,4.1 \ Request 325| 8.4.2 i Analysis 325

I 8.4.3 Design 327| 8.4.4 ; Implementation (Coding) 329

8.5 f Structuring Classes with Inheritance and Polymorphism 331| 8.5,1 Inheritance Hierarchies and Modeling 332I 8.5.2 } Example: A Restricted Savings Account 333| 8.5.3

'

Example; The Dealer and a Player in the Game of Blackjack 335| 8.5.4 | Polymorphic Methods 340| 8.5.5 I Abstract Classes 340| 8.5.6 ; The Costs and Benefits ofObject-Oriented Programming.... 341

8.5 Exercises 343| Summary 343

I Review Questions 345| Projects 34d

[CHAPTER] 9 j GRAPHICAL USER INTERFACES 3499.1 | The Behavior ofTerminal-Based Programs and GUI-Based Programs 350

I 9.1.1 | The Terminal-Based Version 350

| 9.1.2 | The GUI-Based Version 351| 9.1,3 | Event-Driven Programming 353

9.1 | Exercises 3559.2 | Coding Simple GUI-Based Programs 355

| 9.2.1 1 Windows and Labels 356

| 9.2.2 j Displaying Images 357| 9.2.3 | Command Buttons and Responding to Events 358

| 9.2.4 { Viewing the Images of Playing Cards 360

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