Skip to main content

Python regular expressions for humans

Project description

Welcome to python-Rex

Python Rex is regular expressions for humans. (Rex is also abbreviation from re X tended).

Rex is for the re standard module as requests is for urllib module.

Rex also is latin for “king”, and the king of regular expressions is Perl. So Rex API tries to mimic at least some Perl’s idioms.

Supported Python versions: 2.6, 2.7, 3.3


pip install python-rex


pip install -e git+

There are no external dependencies.

from rex import rex


Do that:

from rex import rex
print ("Your ticket number: XyZ-1047. Have fun!" == rex("/[a-z]{3}-(\d{4})/i"))[1]

instead of doing that:

import re
regex = re.compile("[a-z]{3}-(\d{4})", flags=re.IGNORECASE)
m ="Your ticket number: XyZ-1047. Have fun!")

if m is not None:
   print None

# or in shorter way
print if m else None

(both should print 1047).


So far Rex supports:

  • simple matching (first match),
  • substitution,
  • all python re flags.


The most obvious usage - test condition by matching to string:

if 'This is a dog' == rex('/dog/'):
    print 'Oh yeah'


if 'My lucky 777 number' == rex('/[0-9]+/'):
    print 'Number found'

You can use Perl notation and prepend m character to your search:

if 'My lucky 777 number' == rex('m/[0-9]+/'):
    print 'Number found'

but you can also simply check your match:

if ('My lucky 777 number' == rex('m/[0-9]+/'))[0] == '777':
    print 'Number found'

or even groups:

if ('My lucky 777 number' == rex('m/(?P<number>[0-9]+)/'))['number'] == '777':
    print 'Number found'

Remember a mess with re module when it does not match anything? Rex won’t let you down, it will kindly return None for whatever you ask:

>>> print ('My lucky 777 number' == rex('m/(?P<number>[0-9]+)/'))['no_such_group']

>>> print ("I don't tell you my lucky number" == rex('m/(?P<number>[0-9]+)/'))['number']


Substitution can be made by prefixing pattern with s character (like in perl expression):

>>> print "This is a cat" == rex('s/CAT/dog/i')
This is a dog


Every Rex pattern as in Perl patterns allows to suffix some flags, e.g. rex('/pattern/iu') for enabling i and u flag. Rex supports all standard python re flags:

  • d - re.DEBUG
  • i - re.IGNORECASE
  • l - re.LOCALE
  • m - re.MULTILINE
  • s - re.DOTALL
  • u - re.UNICODE
  • x - re.VERBOSE


Rex caches all patterns so reusing patterns is super fast. You can always clear Rex cache by calling rex_clear_cache() or disable caching for specific patterns rex('/pattern/', cache=False).

Rex for orthodox

If you are so orthodox pythonist that couldn’t leave with overloaded == operator syntax in your codebase, you can use “orthodox mode” of rex. Just put the string to match/substitute against as a second argument:

>>> bool(rex("/dog/", "This is a dog"))
>>> rex("s/cat/dog/", "This is a cat")
'This is a dog'

Additionally Rex objects are callable. This is especially useful in situations where you need to process many values against the same regular expression:

>>> my_re = rex("/foo/")
>>> for thing in ["foobar", "bar", "barfoo"]:
...     print bool(my_re(thing))

Project details

Release history Release notifications

This version
History Node


History Node


History Node


History Node


History Node


History Node


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Filename, size & hash SHA256 hash help File type Python version Upload date
python-rex-0.4.tar.gz (3.7 kB) Copy SHA256 hash SHA256 Source None Mar 14, 2014

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging CloudAMQP CloudAMQP RabbitMQ AWS AWS Cloud computing Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page