Regular expressions, or “regex,” is a system for finding complex patterns in text. ... we’ll take a quick tour of the Python regular expression library and how to get the most out of it.

Still, for $3, Patterns is a helpful addition to the toolkit of anyone who builds regular expressions with regularity. If you work with text, you owe it to yourself to learn regular expressions ...

A good book on regular expressions is Mastering Regular Expressions by Jeffrey E. F. Friedl, ISBN 0596528124. It does not explicitly cover Python, but Python’s re module offers very similar ...