Table Of ContentLearn Python Programming
Third Edition
An in-depth introduction to the fundamentals of Python
Fabrizio Romano
Heinrich Kruger
BIRMINGHAM—MUMBAI
Learn Python Programming
Third Edition
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First published: December 2015
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Third edition: October 2021
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"To Elisa, the love of my lives, and to all those who gift the world their beautiful smiles."
Fabrizio Romano
"To my wife, Debi, without whose love, support, and endless patience I would not have been
able to do this."
Heinrich Kruger
Contributors
About the authors
Fabrizio Romano was born in Italy in 1975. He holds a master's degree in
Computer Science Engineering from the University of Padova. He's been working
as a professional software developer since 1999. Fabrizio has been part of Sohonet's
Product Team since 2016. In 2020, the Television Academy honored them with an
Emmy Award in Engineering Development for advancing remote collaboration.
I would like to thank everyone at Packt, and the reviewers, who helped us
in making this book a success. I also want to thank Heinrich Kruger and
Tom Viner for joining me in this adventure. My deepest gratitude goes to
my wife-to-be, Elisa, who never made me feel like I was neglecting her, even
though I was. Thank you for your love and support.
Heinrich Kruger was born in South Africa in 1981. He holds a master's degree in
Computer Science from Utrecht University in the Netherlands. He has been working
as a professional software developer since 2014 and has worked alongside Fabrizio
in the Product Team at Sohonet since 2017.
I want to thank Fabrizio for asking me to help him with this book. It's
been a great experience working with you, my friend. I would also like to
thank Tom Viner and Dong-hee Na for their helpful comments, as well as
everyone at Packt who helped us along the way. Most of all, I thank my
wife, Debi, for all her love, encouragement, and support.
About the reviewers
Tom Viner is a principal software developer living in London. He has over 13
years' experience in building web applications and has been using Python and
Django for 10 years. He has special interests in open-source software, web security,
and test-driven development.
I would like to thank Fabrizio Romano and Heinrich Kruger for inviting me
to review this book.
Dong-hee Na is a software engineer and an open-source enthusiast. He works at
Line Corporation as a backend engineer. He has professional experience in machine
learning projects based on Python and C++. As for his open-source work, he focuses
on the compiler and interpreter area, especially for Python-related projects. He has
been a CPython core developer since 2020.
Table of Contents
Preface xv
Chapter 1: A Gentle Introduction to Python 1
A proper introduction 3
Enter the Python 5
About Python 5
Portability 5
Coherence 5
Developer productivity 6
An extensive library 6
Software quality 6
Software integration 6
Satisfaction and enjoyment 7
What are the drawbacks? 7
Who is using Python today? 8
Setting up the environment 8
Python 2 versus Python 3 8
Installing Python 9
Setting up the Python interpreter 10
About virtual environments 11
Your first virtual environment 13
Installing third-party libraries 15
Your friend, the console 16
How to run a Python program 17
Running Python scripts 17
Running the Python interactive shell 18
Running Python as a service 19
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Table of Contents
Running Python as a GUI application 19
How is Python code organized? 20
How do we use modules and packages? 22
Python's execution model 24
Names and namespaces 24
Scopes 26
Objects and classes 30
Guidelines for writing good code 33
Python culture 34
A note on IDEs 35
Summary 36
Chapter 2: Built-In Data Types 37
Everything is an object 38
Mutable or immutable? That is the question 39
Numbers 40
Integers 40
Booleans 43
Real numbers 44
Complex numbers 46
Fractions and decimals 46
Immutable sequences 48
Strings and bytes 48
Encoding and decoding strings 49
Indexing and slicing strings 50
String formatting 51
Tuples 52
Mutable sequences 54
Lists 54
Bytearrays 57
Set types 59
Mapping types: dictionaries 61
Data types 66
Dates and times 66
The standard library 66
Third-party libraries 71
The collections module 72
namedtuple 72
defaultdict 74
ChainMap 75
Enums 76
Final considerations 77
Small value caching 77
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Table of Contents
How to choose data structures 78
About indexing and slicing 79
About names 81
Summary 81
Chapter 3: Conditionals and Iteration 83
Conditional programming 84
A specialized else: elif 85
The ternary operator 87
Looping 88
The for loop 89
Iterating over a range 89
Iterating over a sequence 90
Iterators and iterables 91
Iterating over multiple sequences 93
The while loop 95
The break and continue statements 98
A special else clause 100
Assignment expressions 102
Statements and expressions 102
Using the walrus operator 103
A word of warning 104
Putting all this together 105
A prime generator 105
Applying discounts 107
A quick peek at the itertools module 111
Infinite iterators 111
Iterators terminating on the shortest input sequence 112
Combinatoric generators 113
Summary 113
Chapter 4: Functions, the Building Blocks of Code 115
Why use functions? 116
Reducing code duplication 117
Splitting a complex task 117
Hiding implementation details 118
Improving readability 119
Improving traceability 120
Scopes and name resolution 121
The global and nonlocal statements 122
Input parameters 124
Argument-passing 125
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