A Beginners Guide to Python 3 Programming

Preface the Second Edition
Preface to the First Edition
	Chapter Organization
	What You Need
	Using an IDE
	Conventions
	Example Code and Sample Solutions
Contents
1 Introduction
	1.1 What is Python?
	1.2 Python Versions
	1.3 Python History
	1.4 Python Programming
	1.5 Python Libraries
	1.6 Python Execution Model
	1.7 Running Python Programs
		1.7.1 Interactively Using the Python Interpreter
		1.7.2 Running a Python File
		1.7.3 Executing a Python Script
		1.7.4 Using Python in an IDE
	1.8 Jupyter Notebooks
	1.9 Useful Resources
2 Where is Python Used
	2.1 Introduction
		2.1.1 Data Analytics
		2.1.2 Machine Learning and AI
		2.1.3 Database Work
		2.1.4 Python for Animation
		2.1.5 Python for Film Making
		2.1.6 Cross Platform UIs
		2.1.7 Games Programming
		2.1.8 Integration Testing Framework
		2.1.9 Academic Research
		2.1.10 Web Services
	2.2 Useful Resources
3 Setting up the Python Environment
	3.1 Introduction
	3.2 Check to See if Python is Installed
	3.3 Installing Python on a Windows PC
		3.3.1 Step 1: Downloading Python
		3.3.2 Step 2: Running the Installer
		3.3.3 Step 3: Set up the PATH (Optional)
		3.3.4 Step 4: Verify the Installation
		3.3.5 Step 5: Run Some Python
		3.3.6 Step 6: Exit the Python Interpreter
	3.4 Setting up on a Mac
	3.5 Setting up an IDE
		3.5.1 Downloading the PyCharm IDE
		3.5.2 Setting up the IDE
	3.6 Writing Python Programs
	3.7 A Note on Filenames
	3.8 Online Resources
4 A First Python Program
	4.1 Introduction
	4.2 Hello World
	4.3 Interactive Hello World
	4.4 Variables
	4.5 Naming Conventions
	4.6 Assignment Operator
	4.7 Python Statements
	4.8 Comments in Code
	4.9 Scripts Versus Programs
	4.10 Online Resources
	4.11 Exercises
5 Python Strings
	5.1 Introduction
	5.2 What Are Strings?
	5.3 Representing Strings
	5.4 What Type is String?
	5.5 What Can You Do with Strings?
		5.5.1 String Concatenation
		5.5.2 Length of a String
		5.5.3 Accessing a Character
		5.5.4 Accessing a Subset of Characters
		5.5.5 Repeating Strings
		5.5.6 Splitting Strings
		5.5.7 Counting Strings
		5.5.8 Replacing Strings
		5.5.9 Finding Sub Strings
		5.5.10 Converting Other Types into Strings
		5.5.11 Remove Prefix and Suffix
		5.5.12 Comparing Strings
		5.5.13 Other String Operations
	5.6 Hints on Strings
		5.6.1 Python Strings are Case Sensitive
		5.6.2 Function/Method Names
		5.6.3 Function/Method Invocations
	5.7 String Formatting
	5.8 String Templates
	5.9 Formatting Using f-strings
	5.10 Online Resources
	5.11 Exercises
6 Numbers, Booleans and None
	6.1 Introduction
	6.2 Types of Numbers
	6.3 Integers
		6.3.1 Converting to Ints
	6.4 Floating Point Numbers
		6.4.1 Converting to Floats
		6.4.2 Converting an Input String into a Floating Point Number
	6.5 Complex Numbers
	6.6 Boolean Values
	6.7 Arithmetic Operators
		6.7.1 Integer Operations
		6.7.2 Negative Number Integer Division
		6.7.3 Floating Point Number Operators
		6.7.4 Integers and Floating Point Operations
		6.7.5 Complex Number Operators
	6.8 Assignment Operators
	6.9 None Value
	6.10 Online Resources
	6.11 Exercises
		6.11.1 General Exercise
		6.11.2 Convert Kilometers to Miles
7 Flow of Control Using if Statements
	7.1 Introduction
	7.2 Comparison Operators
	7.3 Logical Operators
	7.4 The If Statement
		7.4.1 Working with an If Statement
		7.4.2 Else in an If Statement
		7.4.3 The Use of elif
	7.5 Nesting if Statements
	7.6 If Expressions
	7.7 A Note on True and False
	7.8 Hints
	7.9 Online Resources
	7.10 Exercises
		7.10.1 Check Input is Positive or Negative
		7.10.2 Test if a Number is Odd or Even
		7.10.3 Kilometers to Miles Converter
8 Iteration/Looping
	8.1 Introduction
	8.2 While Loop
	8.3 For Loop
		8.3.1 Python for Loops
		8.3.2 Looping by Non-default Increments
		8.3.3 Anonymous Loop Variables
	8.4 Negative Loops
	8.5 Break Loop Statement
	8.6 Continue Loop Statement
	8.7 For Loop with Else
	8.8 A Note on Loop Variable Naming
	8.9 Dice Roll Game
	8.10 Online Resources
	8.11 Exercises
		8.11.1 Calculate the Factorial of a Number
		8.11.2 Print All the Prime Numbers in a Range
9 Number Guessing Game
	9.1 Introduction
	9.2 Setting up the Program
		9.2.1 Create a New Python File
		9.2.2 Add a Welcome Message
		9.2.3 Running the Program
	9.3 What Will the Program Do?
	9.4 Creating the Game
		9.4.1 Generate the Random Number
		9.4.2 Obtain an Input From the User
		9.4.3 Check to See if the Player Has Guessed the Number
		9.4.4 Check They Haven’t Exceeded Their Maximum Number of Guess
		9.4.5 Notify the Player Whether Higher or Lower
		9.4.6 End of Game Status
	9.5 The Complete Listing
	9.6 Hints
		9.6.1 Initializing Variables
		9.6.2 Blank Lines Within a Block of Code
	9.7 Exercises
10 Recursion
	10.1 Introduction
	10.2 Recursive Behaviour
	10.3 Benefits of Recursion
	10.4 Recursively Searching a Tree
	10.5 Recursion in Python
	10.6 Calculating Factorial Recursively
	10.7 Disadvantages of Recursion
	10.8 Online Resources
	10.9 Exercises
11 Introduction to Structured Analysis
	11.1 Introduction
	11.2 Structured Analysis and Function Identification
	11.3 Functional Decomposition
		11.3.1 Functional Decomposition Terminology
		11.3.2 Functional Decomposition Process
		11.3.3 Calculator Functional Decomposition Example
	11.4 Functional Flow
	11.5 Data Flow Diagrams
	11.6 Flowcharts
	11.7 Data Dictionary
	11.8 Online Resources
12 Functions in Python
	12.1 Introduction
	12.2 What are Functions?
	12.3 How Functions Work
	12.4 Types of Functions
	12.5 Defining Functions
		12.5.1 An Example Function
	12.6 Returning Values from Functions
	12.7 Docstring
	12.8 ReStructured Text
	12.9 Function Parameters
		12.9.1 Multiple Parameter Functions
		12.9.2 Default Parameter Values
		12.9.3 Named Arguments
		12.9.4 Arbitrary Arguments
		12.9.5 Positional and Keyword Arguments
	12.10 Anonymous Functions
	12.11 Online Resources
	12.12 Exercises
13 Scope and Lifetime of Variables
	13.1 Introduction
	13.2 Local Variables
	13.3 The Global Keyword
	13.4 Nonlocal Variables
	13.5 Hints
	13.6 Online Resources
	13.7 Exercise
14 Implementing a Calculator Using Functions
	14.1 Introduction
	14.2 What the Calculator Will Do
	14.3 Getting Started
	14.4 The Calculator Operations
	14.5 Behaviour of the Calculator
	14.6 Identifying Whether the User has Finished
	14.7 Selecting the Operation
	14.8 Obtaining the Input Numbers
	14.9 Determining the Operation to Execute
	14.10 Running the Calculator
	14.11 Exercises
15 Introduction to Functional Programming
	15.1 Introduction
	15.2 What is Functional Programming?
	15.3 Advantages to Functional Programming
	15.4 Disadvantages of Functional Programming
	15.5 Referential Transparency
	15.6 Further Reading
16 Higher-Order Functions
	16.1 Introduction
	16.2 Recap on Functions in Python
	16.3 Functions as Objects
	16.4 Higher-Order Function Concepts
		16.4.1 Higher-Order Function Example
	16.5 Python Higher-Order Functions
		16.5.1 Using Higher-Order Functions
		16.5.2 Functions Returning Functions
	16.6 Online Resources
	16.7 Exercises
17 Curried Functions
	17.1 Introduction
	17.2 Currying Concepts
	17.3 Python and Curried Functions
	17.4 Closures
	17.5 Online Resources
	17.6 Exercises
18 Introduction to Object Orientation
	18.1 Introduction
	18.2 Classes
	18.3 What Are Classes for?
		18.3.1 What Should a Class Do?
		18.3.2 Class Terminology
	18.4 How is an OO System Constructed?
		18.4.1 Where Do We Start?
		18.4.2 Identifying the Objects
		18.4.3 Identifying the Services or Methods
		18.4.4 Refining the Objects
		18.4.5 Bringing It All Together
	18.5 Where Is the Structure in an OO Program?
	18.6 Further Readings
19 Python Classes
	19.1 Introduction
	19.2 Python and Classes
	19.3 Class Definitions
	19.4 Creating Examples of the Class Person
	19.5 Be Careful with Assignment
	19.6 Printing Out Objects
		19.6.1 Accessing Object Attributes
		19.6.2 Defining a Default String Representation
		19.6.3 Defining a Default Storage Representation
	19.7 Providing a Class Comment
	19.8 Adding a Birthday Method
	19.9 Defining Instance Methods
	19.10 Person Class Recap
	19.11 The Del Keyword
	19.12 Automatic Memory Management
	19.13 Intrinsic Attributes
	19.14 Online Resources
	19.15 Exercises
20 Class Side and Static Behaviour
	20.1 Introduction
	20.2 Class-Side Data
	20.3 Class-Side Methods
		20.3.1 Why Class-Side Methods?
	20.4 Static Methods
	20.5 Hints
	20.6 Online Resources
	20.7 Exercises
21 Class Inheritance
	21.1 Introduction
	21.2 What is Inheritance?
	21.3 Defining Inheritance Between Classes
	21.4 Terminology Around Inheritance
		21.4.1 Types of Hierarchy
	21.5 The Class Object and Inheritance
	21.6 The Built-in Object Class
	21.7 Purpose of Subclasses
	21.8 Overriding Methods
	21.9 Extending Superclass Methods
	21.10 Inheritance-Oriented Naming Conventions
	21.11 Python and Multiple Inheritance
	21.12 Multiple Inheritance Considered Harmful
	21.13 Summary
	21.14 Online Resources
	21.15 Exercises
22 Why Bother with Object Orientation?
	22.1 Introduction
	22.2 The Procedural Approach
		22.2.1 Procedures for the Data Structure
		22.2.2 Packages
	22.3 Does Object Orientation Do Any Better?
		22.3.1 Packages Versus Classes
		22.3.2 Inheritance
	22.4 Summary
23 Operator Overloading
	23.1 Introduction
	23.2 Operator Overloading
		23.2.1 Why Have Operator Overloading?
		23.2.2 Why not Have Operator Overloading?
		23.2.3 Implementing Operator Overloading
	23.3 Numerical Operators
	23.4 Comparison Operators
	23.5 Logical Operators
	23.6 Summary
	23.7 Online Resources
	23.8 Exercises
24 Python Properties
	24.1 Introduction
	24.2 Python Attributes
	24.3 Setter and Getter Style Methods
	24.4 Public Interface to Properties
	24.5 More Concise Property Definitions
	24.6 Online Resources
	24.7 Exercises
25 Abstract Base Classes
	25.1 Introduction
	25.2 Abstract Classes as a Concept
	25.3 Abstract Base Classes in Python
		25.3.1 Subclassing an ABC
		25.3.2 Defining an Abstract Base Class
	25.4 Defining an Interface
	25.5 Virtual Subclasses
	25.6 Mixins
	25.7 Online Resources
26 Error and Exception Handling
	26.1 Introduction
	26.2 Errors and Exceptions
	26.3 What is an Exception?
	26.4 What is Exception Handling?
	26.5 Handling an Exception
		26.5.1 Accessing the Exception Object
		26.5.2 Jumping to Exception Handlers
		26.5.3 Catch Any Exception
		26.5.4 The Else Clause
		26.5.5 The Finally Clause
	26.6 Raising an Exception
	26.7 Defining an Custom Exception
	26.8 Chaining Exceptions
	26.9 Exception Groups
	26.10 Exception Group Handling
	26.11 Exception Notes
	26.12 Generate a Traceback Programmatically
	26.13 Online Resources
	26.14 Exercises
27 Python Modules and Packages
	27.1 Introduction
	27.2 Modules
	27.3 Python Modules
	27.4 Importing Python Modules
		27.4.1 Importing a Module
		27.4.2 Importing from a Module
		27.4.3 Importing Aliases
		27.4.4 Hiding Some Elements of a Module
		27.4.5 Importing Within a Function
	27.5 Module Properties
	27.6 Standard Modules
	27.7 Python Module Search Path
	27.8 Modules as Scripts
	27.9 Python Packages
		27.9.1 Package Organization
		27.9.2 Sub Packages
	27.10 Online Resources
	27.11 Exercise
28 Protocols, Polymorphism and Descriptors
	28.1 Introduction
	28.2 Implicit Contracts
	28.3 Duck Typing
	28.4 Polymorphism
	28.5 Protocols
	28.6 The Length Protocol
	28.7 The Sequence Protocol
	28.8 The Context Manager Protocol
	28.9 The Descriptor Protocol
	28.10 Online Resources
	28.11 Exercises
29 Decorators
	29.1 Introduction
	29.2 What Are Decorators?
	29.3 Defining a Decorator
	29.4 Using Decorators
	29.5 Functions with Parameters
	29.6 Stacked Decorators
	29.7 Parameterized Decorators
	29.8 Method Decorators
		29.8.1 Methods Without Parameters
		29.8.2 Methods with Parameters
	29.9 Class Decorators
	29.10 When is a Decorator Executed?
	29.11 Built-In Decorators
	29.12 FuncTools Wrap
	29.13 Online Resources
	29.14 Book Reference
	29.15 Exercises
30 Iterables and Iterators
	30.1 Introduction
	30.2 Iteration
		30.2.1 Iterables
		30.2.2 Iterators
		30.2.3 The Iteration Related Methods
		30.2.4 The Iterable Evens Class
		30.2.5 Using the Evens Class with a For Loop
	30.3 The Itertools Module
	30.4 Online Resources
31 Generators and Coroutines
	31.1 Introduction
	31.2 Generators
		31.2.1 Defining a Generator Function
		31.2.2 Using a Generator Function in a for Loop
		31.2.3 When Do the Yield Statements Execute?
		31.2.4 An Even Number Generator
		31.2.5 Nesting Generator Functions
		31.2.6 Using Generators Outside a for Loop
	31.3 Coroutines
	31.4 Exercises
32 Collections, Tuples and Lists
	32.1 Introduction
	32.2 Python Collection Types
	32.3 Characterising Collections
	32.4 Tuples
		32.4.1 Creating Tuples
		32.4.2 The Tuple() Constructor Function
		32.4.3 Accessing Elements of a Tuple
		32.4.4 Creating New Tuples from Existing Tuples
		32.4.5 Tuples Can Hold Different Types
		32.4.6 Iterating Over Tuples
		32.4.7 Tuple Related Functions
		32.4.8 Checking if an Element Exists
		32.4.9 Nested Tuples
		32.4.10 Things You Can’t Do with Tuples
	32.5 Lists
		32.5.1 Creating Lists
		32.5.2 List Constructor Function
		32.5.3 Accessing Elements from a List
		32.5.4 Adding to a List
		32.5.5 Inserting into a List
		32.5.6 List Concatenation
		32.5.7 Removing from a List
		32.5.8 The Pop() Method
		32.5.9 Deleting from a List
		32.5.10 List Methods
	32.6 Online Resources
	32.7 Exercises
33 Sets
	33.1 Introduction
	33.2 Creating a Set
	33.3 The Set() Constructor Function
	33.4 Accessing Elements in a Set
	33.5 Working with Sets
		33.5.1 Checking for Presence of an Element
		33.5.2 Adding Items to a Set
		33.5.3 Changing Items in a Set
		33.5.4 Obtaining the Length of a Set
		33.5.5 Obtaining the Max and Min Values in a Set
		33.5.6 Removing an Item
	33.6 Nesting Lists Within Sets
	33.7 Set Operations
	33.8 Set Methods
	33.9 Online Resources
	33.10 Exercises
34 Dictionaries
	34.1 Introduction
	34.2 What is a Dictionary
	34.3 Creating a Dictionary
		34.3.1 The dict() Constructor Function
	34.4 Working with Dictionaries
		34.4.1 Accessing Items via Keys
		34.4.2 Adding a New Entry
		34.4.3 Changing a Keys Value
		34.4.4 Removing an Entry
		34.4.5 Iterating Over Keys
		34.4.6 Values, Keys and Items
		34.4.7 Checking Key Membership
		34.4.8 Obtaining the Length of a Dictionary
		34.4.9 Nesting Dictionaries
		34.4.10 Checking to See if a Key is Present
	34.5 Dictionary Operators Added in 3.9
	34.6 A Note on Dictionary Key Objects
	34.7 Dictionary Methods
	34.8 Online Resources
	34.9 Exercises
35 Frozensets
	35.1 Introduction
	35.2 Frozenset Characteristics
	35.3 Creating a Frozenset
	35.4 Frozenset Operations
	35.5 Using Frozensets with Sets
36 Collection Related Modules
	36.1 Introduction
	36.2 List Comprehension
	36.3 The Collections Module
		36.3.1 The Counter Container
		36.3.2 The Defaultdict Container
		36.3.3 The Namedtuple Container
	36.4 The Itertools Module
	36.5 Online Resources
	36.6 Exercises
37 ADTs, Queues and Stacks
	37.1 Introduction
	37.2 Abstract Data Types
	37.3 Data Structures
	37.4 Queues
		37.4.1 Python List as a Queue
		37.4.2 Defining a Queue Class
	37.5 Stacks
		37.5.1 Python List as a Stack
	37.6 Online Resources
	37.7 Exercises
38 Map, Filter and Reduce
	38.1 Introduction
	38.2 Filter
	38.3 Map
	38.4 Reduce
	38.5 Online Resources
	38.6 Exercises
39 Sorting and Higher-Order Functions
	39.1 Introduction
	39.2 The sorted() Function
	39.3 Sorting in Reverse Order
	39.4 The sort() Method
	39.5 Reversing the sort() Method
	39.6 Changing the Sort Key
	39.7 Sorting Containers of Containers
	39.8 Exercises
40 Python Enumerated Values
	40.1 Introduction
	40.2 What is an Enumeration?
	40.3 Creating an Enumeration Using Class Syntax
	40.4 Enum Values
	40.5 Using the Name and Value Attributes
	40.6 Creating an Enumeration Using the Function Call Syntax
	40.7 Creating Enumerations from Automatic Values
	40.8 Working with Enum Aliases
	40.9 Enumerations Unique Values
	40.10 Iterating Through Enumeration Values
	40.11 Comparing Enumerations
	40.12 Integer Enumerations with IntEnum
	40.13 Exercises
41 Structural Pattern Matching
	41.1 Introduction
	41.2 Basic Pattern Matching
	41.3 Default Case
	41.4 Capture Default Case
	41.5 Alternative Values in Case Condition
	41.6 Matching Sequences/Containers
	41.7 Structural Matching and Lists
	41.8 Matching Alternative Sequences/Containers
	41.9 Matching Multiple Options Within a Container
	41.10 Guards on a Case Condition
	41.11 Exercises
42 Python Virtual Environments
	42.1 Introduction
	42.2 Third-Party Libraries
	42.3 The Pip Tool
		42.3.1 Finding the Pip Version
		42.3.2 Installing Pip
		42.3.3 Updating Pip
	42.4 Default Installation
	42.5 Pip Virtual Environments
	42.6 Installing Modules
	42.7 Listing and Freezing on Modules
		42.7.1 The pip list Command
		42.7.2 The pip inspect Command
		42.7.3 The pip freeze Command
	42.8 Uninstalling Modules
	42.9 Module Path Search Order
	42.10 Using PyCharm with Virtual Environments
	42.11 Online Resources
43 Monkey Patching
	43.1 Introduction
	43.2 What is Monkey Patching?
		43.2.1 How Does Monkey Patching Work?
		43.2.2 Monkey Patching Example
		43.2.3 The Self Parameter
		43.2.4 Adding New Data to a Class
	43.3 Online Resources
44 Attribute Lookup
	44.1 Introduction
	44.2 Attributes in Python
	44.3 Handling Unknown Attribute Access
	44.4 Handling Unknown Method Invocations
	44.5 Intercepting Attribute Lookup
	44.6 Intercepting Setting an Attribute
	44.7 Exercises
45 The Python Bites Back
	45.1 Fourteen Beginner Mistakes to Avoid in Python
	45.2 Mistake #1: Indentation
	45.3 Mistake #2: Case Sensitivity
	45.4 Mistake #3: Default Initialization of Function/Method Parameters with Mutable Types
	45.5 Mistake #4: Default Initialization of Function/Method Parameters Using a Function
	45.6 Mistake #5: Out by 1 Ranges
	45.7 Mistake #5: Assignment Operator Versus Equality Operator
	45.8 Mistake #6: Falsey and Truthy
	45.9 Mistake #7: Hiding Built-In Functions and Classes
	45.10 Mistake #8: Hiding Built-In Modules
	45.11 Mistake #9: Function Reference Versus Function Call
	45.12 Mistake #10: Modifying a List While Iterating Over It
	45.13 Mistake #11: Sets Can Only Contain Immutable Objects
	45.14 Mistake #12: Local Versus Global Variables
	45.15 Mistake #13: Referencing Nonlocal Variable
	45.16 Mistake #14: Copying a Mutable Type
46 TicTacToe Game
	46.1 Introduction
	46.2 Classes in the Game
	46.3 Counter Class
	46.4 Move Class
	46.5 The Player Class
	46.6 The HumanPlayer Class
	46.7 The ComputerPlayer Class
	46.8 The Board Class
	46.9 The Game Class
	46.10 Running the Game