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

Partials


We already know that we can apply unary functions to multiple elements using map, and apply binary functions using reduce.

There is a whole set of functions that accepts a callable in Python and applies it to a set of items.

The major problem is that frequently the callable we want to apply might have a slightly different signature, and while we can solve the issue by wrapping the callable into another callable that adapts the signature, this is not very convenient if you just want to apply a function to a set of items.

For example, if you want to multiply all numbers in a list by 3, there is no function that multiplies a given argument by 3.

How to do it...

We can easily adapt operator.mul to be a unary function and then pass it to map to apply it to the whole list:

>>> import functools, operator
>>>
>>> values = range(10)
>>> mul3 = functools.partial(operator.mul, 3)
>>> list(map(mul3, values))
[0, 3, 6, 9, 12, 15, 18, 21, 24, 27]

As you can...