Book Image

Modern Python Cookbook - Second Edition

By : Steven F. Lott
Book Image

Modern Python Cookbook - Second Edition

By: Steven F. Lott

Overview of this book

Python is the preferred choice of developers, engineers, data scientists, and hobbyists everywhere. It is a great language that can power your applications and provide great speed, safety, and scalability. It can be used for simple scripting or sophisticated web applications. By exposing Python as a series of simple recipes, this book gives you insight into specific language features in a particular context. Having a tangible context helps make the language or a given standard library feature easier to understand. This book comes with 133 recipes on the latest version of Python 3.8. The recipes will benefit everyone, from beginners just starting out with Python to experts. You'll not only learn Python programming concepts but also how to build complex applications. The recipes will touch upon all necessary Python concepts related to data structures, object oriented programming, functional programming, and statistical programming. You will get acquainted with the nuances of Python syntax and how to effectively take advantage of it. By the end of this Python book, you will be equipped with knowledge of testing, web services, configuration, and application integration tips and tricks. You will be armed with the knowledge of how to create applications with flexible logging, powerful configuration, command-line options, automated unit tests, and good documentation.
Table of Contents (18 chapters)
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Extending a built-in collection – a list that does statistics

In the Designing classes with lots of processing recipe, we looked at a way to distinguish between a complex algorithm and a collection. We showed how to encapsulate the algorithm and the data into separate classes. The alternative design strategy is to extend the collection to incorporate a useful algorithm.

How can we extend Python's built-in collections? How can we add features to the built-in list?

Getting ready

We'll create a sophisticated list class where each instance can compute the sums and averages of the items in the list. This will require an application to only put numbers in the list; otherwise, there will be ValueError exceptions.

We're going to show methods that explicitly use generator expressions as places where additional processing can be included. Rather than use sum(self), we're going to emphasize sum(v for v in self) because there are two common future extensions...