Regex and Python re

Regex

A regular expression (regex) is a sequence of characters that define a search pattern.

RexEgg - Regex Syntax

RegExr - Regex Testing

re library

The python re module provides regular expression matching operations similar to those found in Perl.

Documentation

import re

re.match()

Match is anchored to the beginning of the string, so it will only find a pattern if it starts at the beginning of the string.

If zero or more characters at the beginning of string match the regular expression pattern, return a corresponding match object. Return None if the string does not match the pattern; note that this is different from a zero-length match.

Note that even in MULTILINE mode, re.match() will only match at the beginning of the string and not at the beginning of each line.

If you want to locate a match anywhere in string, use search() instead (see also search() vs. match()).

Source

re.match(regex, element)

The above code results in a match object that looks like this:

<re.Match object; span=(0, 5), match='Match result'>

Span: The start and end of the result.

Match: The string showing the found result.

In order to simply confirm if there is a match without showing the match object, you can use:

bool(re.match(regex, element))

results in a True or False output depending on whether or not a match is found.

re.search()

Scan through string looking for the first location where the regular expression pattern produces a match, and return a corresponding match object. Return None if no position in the string matches the pattern; note that this is different from finding a zero-length match at some point in the string.

re.search(regex, element)

This returns a list of strings

['result1', 'result2']