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I’d like to dedicate this book to my parents – may this bring joy and happiness into their lives. CONTENTS Preface xvii Chapter 1 Introduction to Python 3 1 1.1 Tools for Python 2 1.1.1 easy_install and pip 3 1.1.2 virtualenv 3 1.1.3 IPython 3 1.2 Python Installation 4 1.3 Setting the PATH Environment Variable (Windows Only) 5 1.4 Launching Python on Your Machine 5 1.4.1 The Python Interactive Interpreter 5 1.5 Python Identifiers 6 1.6 Lines, Indentation, and Multilines 7 1.7 Quotation and Comments in Python 8 1.8 Saving Your Code in a Module 9 1.9 Some Standard Modules in Python 10 1.10 The help() and dir() Functions 11 1.11 Compile Time and Runtime Code Checking 12 1.12 Simple Data Types in Python 13 1.13 Working with Numbers 13 1.13.1 Working with Other Bases 15 1.13.2 The chr() Function 15 1.13.3 The round() Function in Python 16 1.13.4 Formatting Numbers in Python 16 1.14 Working with Fractions 17 1.15 Unicode and UTF-8 18 1.16 Working with Unicode 18 1.17 Working with Strings 19 1.17.1 Comparing Strings 21 1.17.2 Formatting Strings in Python 21 1.18 Uninitialized Variables and the Value None in Python 22 1.19 Slicing Strings 22 1.19.1 Testing for Digits and Alphabetic Characters 23 1.20 Search and Replace a String in Other Strings 24 1.21 Remove Leading and Trailing Characters 25 1.22 Printing Text without NewLine Characters 26 1.23 Text Alignment 27 1.24 Working with Dates 27 1.24.1 Converting Strings to Dates 29 viii • CONTENTS 1.25 Exception Handling in Python 29 1.26 Handling User Input 31 1.27 Command-Line Arguments 33 1.28 Summary 35 Chapter 2 Conditional Logic, Loops, and Functions 37 2.1 Precedence of Operators in Python 38 2.2 Python Reserved Words 39 2.3 Working with Loops in Python 39 2.3.1 Python for Loops 39 2.3.2 A for Loop with try/except in Python 40 2.3.3 Numeric Exponents in Python 41 2.4 Nested Loops 42 2.5 The split() Function with for Loops 43 2.6 Using the split() Function to Compare Words 43 2.7 Using the split() Function to Print Justified Text 44 2.8 Using the split() Function to Print Fixed Width Text 45 2.9 Using the split() Function to Compare Text Strings 47 2.10 Using a Basic for Loop to Display Characters in a String 48 2.11 The join() Function 48 2.12 Python while Loops 49 2.13 Conditional Logic in Python 50 2.14 The break/continue/pass Statements 50 2.15 Comparison and Boolean Operators 51 2.15.1 The in/not in/is/is not Comparison Operators 51 2.15.2 The and, or, and not Boolean Operators 52 2.16 Local and Global Variables 52 2.17 Scope of Variables 53 2.18 Pass by Reference versus Value 55 2.19 Arguments and Parameters 56 2.20 Using a while loop to Find the Divisors of a Number 56 2.20.1 Using a while loop to Find Prime Numbers 57 2.21 User-Defined Functions in Python 58 2.22 Specifying Default Values in a Function 59 2.22.1 Returning Multiple Values from a Function 60 2.23 Functions with a Variable Number of Arguments 60 2.24 Lambda Expressions 61 2.25 Recursion 62 2.25.1 Calculating Factorial Values 62 2.25.2 Calculating Fibonacci Numbers 63 2.25.3 Calculating the GCD of Two Numbers 64 2.25.4 Calculating the LCM of Two Numbers 65 2.26 Summary 66 CONTENTS • ix Chapter 3 Python Collections 67 3.1 Working with Lists 68 3.1.1 Lists and Basic Operations 68 3.1.2 Reversing and Sorting a List 70 3.1.3 Lists and Arithmetic Operations 71 3.1.4 Lists and Filter-Related Operations 72 3.2 Sorting Lists of Numbers and Strings 73 3.3 Expressions in Lists 74 3.4 Concatenating a List of Words 74 3.5 The BubbleSort in Python 75 3.6 The Python range() Function 76 3.6.1 Counting Digits, Uppercase, and Lowercase Letters 76 3.7 Arrays and the append() Function 77 3.8 Working with Lists and the split()Function 78 3.9 Counting Words in a List 79 3.10 Iterating through Pairs of Lists 79 3.11 Other List-Related Functions 80 3.12 Using a List as a Stack and a Queue 82 3.13 Working with Vectors 83 3.14 Working with Matrices 84 3.15 The NumPy Library for Matrices 85 3.16 Queues 86 3.17 Tuples (Immutable Lists) 87 3.18 Sets 88 3.19 Dictionaries 89 3.19.1 Creating a Dictionary 89 3.19.2 Displaying the Contents of a Dictionary 90 3.19.3 Checking for Keys in a Dictionary 90 3.19.4 Deleting Keys from a Dictionary 91 3.19.5 Iterating through a Dictionary 91 3.19.6 Interpolating Data from a Dictionary 92 3.20 Dictionary Functions and Methods 92 3.21 Dictionary Formatting 92 3.22 Ordered Dictionaries 93 3.22.1 Sorting Dictionaries 93 3.22.2 Python Multidictionaries 94 3.23 Other Sequence Types in Python 94 3.24 Mutable and Immutable Types in Python 95 3.25 The type() Function 96 3.26 Summary 97 Chapter 4 Introduction to NumPy and Pandas 99 4.1 What is NumPy? 101 4.1.1 Useful NumPy Features 101 x • CONTENTS 4.2 What are NumPy Arrays? 102 4.3 Working with Loops 103 4.4 Appending Elements to Arrays (1) 104 4.5 Appending Elements to Arrays (2) 105 4.6 Multiply Lists and Arrays 106 4.7 Doubling the Elements in a List 106 4.8 Lists and Exponents 107 4.9 Arrays and Exponents 107 4.10 Math Operations and Arrays 108 4.11 Working with “-1” Subranges with Vectors 109 4.12 Working with “-1” Subranges with Arrays