Python regular expressions cheatsheet

py_re.py

import re

# ---------------------------------------------------------------------------- #
# Regex sting substitution
#
# As a first example, lets say we have a jinja2 template that needs
# a particular section(s) replaced

LEFT_NAV = re.compile(r'{{\s*left_nav\s*}}')

def replace_left_nav(template_contents):
    ''' Pass me an unrendered block of content, and i will replace:
    {{ left_nav }} with {% include "left_nav.html" %}
    '''

    # Since we already compiled our LEFT_NAV regex above, we use that in place
    # of re.sub. First param is what you will put in place of LEFT_NAV, and
    # finally the long string to look through for matches.
    # Note this will replace all instances it finds. You can specify a
    # parameter count to the sub function to limit this. Also see:
    # http://docs.python.org/2/library/re.html
    new_contents = LEFT_NAV.sub('{% include "left_nav.html" %}', template_contents)