Those evil utm_ parameters ...

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import re

UTM_TAGS = (
    u'utm_source',
    u'utm_medium',
    u'utm_term',
    u'utm_content',
    u'utm_campaign'
    )

utm_re = list()
for ut in UTM_TAGS:
    # unescaped form: &utm_name=value
    utm_re.append(re.compile(u"([?&]"+ut+u"=[^&]*)"))
    # escaped form: &utm_name=value
    utm_re.append(re.compile(u"(&"+ut+u"=[^&]*)"))

def unUTM(url):
    # check if the URL is parameterized
    if 0 <= url.find("?"):
        # double the parameter delimiter, so we won't lose it
        url = url.replace("?", "??")
        for p in utm_re:
            url = p.sub(u"", url)
        # clean up leftover mess
        url = url.replace("??","?").replace("?&", "?").strip("?")
    return(url)

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import re

UTM_TAGS = (
    u'utm_source',
    u'utm_medium',
    u'utm_term',
    u'utm_content',
    u'utm_campaign'
    )

utm_re = re.compile(u''.join((
    u'(^|&(amp;)?)(',      # either at start or preceeded by '&' or '&'
    u'|'.join(UTM_TAGS),   # all tags as alternatives
    u'=)[^&]*'             # followed by '=' and all chars upto next '&'
    )))

def unUTM(url):
    # check if the URL is parameterized
    if '?' in url:
        (url, params) = url.split('?', 1)
        params = utm_re.sub(u'', params)
        if '' != params:
            params = re.compile(u'^&(amp;)?').sub(u'', params)
            url = u'?'.join((url, params))
    return(url)

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from urlparse import parse_qs, urlsplit, urlunsplit
from urllib import urlencode
from cgi import escape

def unUTM(url):
    res = urlsplit(url)
    if not res.query:
        return url
    qdict = parse_qs(res.query)
    map(lambda key: qdict.pop(key), filter(lambda key: key.startswith('utm_'), qdict.keys()))
    res = list(res))
    res[3] = escape(urlencode(qdict, doseq=1))
    return urlunsplit(res)