Mastering Python Regular Expressions: For Python developers, this concise and down-to-earth guide to regular expressions

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Paperback Feb 2014 110 pages Edition

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Paperback Feb 2014 110 pages Edition

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Mastering Python Regular Expressions

Chapter 2. Regular Expressions with Python

In the previous chapter, we've seen how generic regular expressions work. In this chapter, we walk you through all the operations Python provides us with to work with regular expressions and how Python deals with them.

To do so, we will see the quirks of the language when dealing with regular expressions, the different types of strings, the API it offers through the RegexObject and MatchObject classes, every operation that we can do with them in depth with many examples, as well as some problems generally faced by users. Lastly, we will see the small nuances and differences between Python and other regex engines and between Python 2 and Python 3.

Compilation flags

When compiling a pattern string into a pattern object, it's possible to modify the standard behavior of the patterns. In order to do that, we have to use the compilation flags. These can be combined using the bitwise OR "|".

Flag	Python	Description
`re.IGNORECASE` or `re.I`	2.x 3.x	The pattern will match lower case and upper case.
`re.MULTILINE` or `re.M`	2.x 3.x	This flag changes the behavior of two metacharacters: `^`: Which now matches at the beginning of the string and at the beginning of each new line. `$`: In this case, it matches at the end of the string and the end of each line. Concretely, it matches right before the newline character.
`re.DOTALL` or `re.S`	2.x 3.x	The metacharacter "`.`" will match any character even the newline.
`re.LOCALE` or `re.L`	2.x 3.x	This flag makes \w, \W, \b, \B, \s, and \S dependent on the current locale. "re.LOCALE just passes the character to the underlying C library. It really only works on bytestrings which have 1 byte per character. UTF...

Description

Regular expressions are used by many text editors, utilities, and programming languages to search and manipulate text based on patterns. They are considered the Swiss army knife of text processing. Powerful search, replacement, extraction and validation of strings, repetitive and complex tasks are reduced to a simple pattern using regular expressions. Mastering Python Regular Expressions will teach you about Regular Expressions, starting from the basics, irrespective of the language being used, and then it will show you how to use them in Python. You will learn the finer details of what Python supports and how to do it, and the differences between Python 2.x and Python 3.x. The book starts with a general review of the theory behind the regular expressions to follow with an overview of the Python regex module implementation, and then moves on to advanced topics like grouping, looking around, and performance. You will explore how to leverage Regular Expressions in Python, some advanced aspects of Regular Expressions and also how to measure and improve their performance. You will get a better understanding of the working of alternators and quantifiers. Also, you will comprehend the importance of grouping before finally moving on to performance optimization techniques like the RegexBuddy Tool and Backtracking. Mastering Python Regular Expressions provides all the information essential for a better understanding of Regular Expressions in Python.

Who is this book for?

This book is aimed at Python developers who want to learn how to leverage Regular Expressions in Python. Basic knowledge of Python is required for a better understanding.

What you will learn

Explore the regular expressions syntax
Improve the readability and future maintenance of the regex
Find solutions for typical problems with regular expressions
Familiarize yourself with match and search operations
Leverage the look around technique to create powerful regular expressions
Gain insight on the uses of Groups
Get to know how the regex engine works through the Backtracking process
Enhance the performance of your regular expressions

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New Media Aug 06, 2018

Great Learning tool.

Amazon Verified review

Javier Angulo Lucerón Jun 16, 2014

It's a really well written book, with tons of examples to allow you understand from the basics to the most advanced features. I'm starting to leverage regular expressions thanks to this book, quite recommended.

Doc Jun 19, 2018

I used this book to learn and master regular expressions in Python. It is easy to follow and if you study each chapter carefully you will master regular expressions. It starts out with a brief overview of regex and then transitions to specific application of regex in python. Also great to have as a desk reference.

Uncle Buck Sep 24, 2015

If you are getting started with regular expressions the first chapter of this book is worth the price of the book in itself.I cannot praise this book enough. The well written and clear examples are fantastic. I've been struggling with regular expressions for a while but this book is a god send. Thank you Felix Lopez!!!!!

DR Jan 05, 2020

A great, concise and thorough book on using Regex in Python. Excellent, thoroughly recommended.

Mastering Python Regular Expressions: For Python developers, this concise and down-to-earth guide to regular expressions

What do you get with Print?

Mastering Python Regular Expressions

Chapter 2. Regular Expressions with Python

A brief introduction

Tip

Backslash in string literals

Building blocks for Python regex

RegexObject

Compilation flags

Python and regex special considerations

Differences between Python and other flavors

Unicode

Summary

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