Book Image

Secret Recipes of the Python Ninja

Book Image

Secret Recipes of the Python Ninja

Overview of this book

This book covers the unexplored secrets of Python, delve into its depths, and uncover its mysteries. You’ll unearth secrets related to the implementation of the standard library, by looking at how modules actually work. You’ll understand the implementation of collections, decimals, and fraction modules. If you haven’t used decorators, coroutines, and generator functions much before, as you make your way through the recipes, you’ll learn what you’ve been missing out on. We’ll cover internal special methods in detail, so you understand what they are and how they can be used to improve the engineering decisions you make. Next, you’ll explore the CPython interpreter, which is a treasure trove of secret hacks that not many programmers are aware of. We’ll take you through the depths of the PyPy project, where you’ll come across several exciting ways that you can improve speed and concurrency. Finally, we’ll take time to explore the PEPs of the latest versions to discover some interesting hacks.
Table of Contents (17 chapters)
Title Page
Copyright and Credits
Packt Upsell
Foreword
Contributors
Preface
Index

Using the itertools module


Beyond just the standard iteration protocol, Python also provides the itertools module. This module provides a number of iterator building blocks that, used singly or in combination, can create specialized iteration tools for efficient looping.

How to do it...

There are three main categories of itertools: infinite iterators, combinatoric iterators, and iterators that terminate on the shortest input sequence.

Infinite iterators

Infinite iterators return values repeatedly until a terminating condition is reached:

  1. The count(start=0, step=1) function returns evenly spaced values that start at the start argument provided. Stepping is provided to allow skipping values. This function is frequently used with map() to generate consecutive data points. When used with zip(), it can be used to add sequence numbers:

    • In this example, we import the count() function from the itertools module in line 54.
    • In line 55, we create a counting loop, starting with the integer 5 and a stepping...