Book Image

Modern Python Standard Library Cookbook

By : Alessandro Molina
Book Image

Modern Python Standard Library Cookbook

By: Alessandro Molina

Overview of this book

The Python 3 Standard Library is a vast array of modules that you can use for developing various kinds of applications. It contains an exhaustive list of libraries, and this book will help you choose the best one to address specific programming problems in Python. The Modern Python Standard Library Cookbook begins with recipes on containers and data structures and guides you in performing effective text management in Python. You will find Python recipes for command-line operations, networking, filesystems and directories, and concurrent execution. You will learn about Python security essentials in Python and get to grips with various development tools for debugging, benchmarking, inspection, error reporting, and tracing. The book includes recipes to help you create graphical user interfaces for your application. You will learn to work with multimedia components and perform mathematical operations on date and time. The recipes will also show you how to deploy different searching and sorting algorithms on your data. By the end of the book, you will have acquired the skills needed to write clean code in Python and develop applications that meet your needs.
Table of Contents (21 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Grouping similar items


Sometimes you might face a list of entries that has multiple, repeated entries and you might want to group the similar ones based on some kind of property.

For example, here is a list of names:

names = [('Alex', 'Zanardi'),
         ('Julius', 'Caesar'),
         ('Anakin', 'Skywalker'),
         ('Joseph', 'Joestar')]

We might want to build a group of all people whose names start with the same character, so we can keep our phone book in alphabetical order instead of having names randomly scattered here and there.

How to do it...

The itertools module is again a very powerful tool that provides us with the foundations we need to handle iterables:

import itertools

def group_by_key(iterable, key):
    iterable = sorted(iterable, key=key)
    return {k: list(g) for k,g in itertools.groupby(iterable, key)}

Given our list of names, we can apply a key function that grabs the first character of the name so that all entries will be grouped by it:

>>> group_by_key(names, lambda...