As @bereal commented use the Regular Expression module re.sub.

Here's a simple example

Python:

>>> import re
>>> re.sub(r'([^A-Z])([A-Z])', r'\1_\2', 'camelCase').lower()
'camel_case'

And just for kicks here's it on PHP too:

<?php
echo strtolower(preg_replace('/([^A-Z])([A-Z])/', '$1_$2', 'camelCase'));
// prints camel_case

Python's re.sub doesn't support array-style inputs the way PHP's preg_replace does. You would need to iterate over the replacements instead e.g.

def clean(text):
    utf8 = {
        '[áàâãªä]'   :   'a',
        '[ÁÀÂÃÄ]'    :   'A',
        '[ÍÌÎÏ]'     :   'I',
        '[íìîï]'     :   'i',
        '[éèêë]'     :   'e',
        '[ÉÈÊË]'     :   'E',
        '[óòôõºö]'   :   'o',
        '[ÓÒÔÕÖ]'    :   'O',
        '[úùûü]'     :   'u',
        '[ÚÙÛÜ]'     :   'U',
        'ç'          :   'c',
        'Ç'          :   'C',
        'ñ'          :   'n',
        'Ñ'          :   'N',
        '–'          :   '-', # UTF-8 hyphen to "normal" hyphen
        '[’‘‹›‚]'    :   ' ', # Literally a single quote
        '[“”«»„]'    :   ' ', # Double quote
        ' '          :   ' ', # nonbreaking space (equiv. to 0x160)
    }
    text = text.strip()
    for pat, repl in utf8.items():
        text = re.sub(pat, repl, text, 0, re.U)
    return text

Note also that python does not use delimiters around regexes, and you pass the u flag to re.sub directly. I've adjusted your code to deal with those issues.

Sample usage:

print(clean('ÂôÑ‹Î'))

Output:

AoN I

No. Regular expressions in Python are handled by the re module.

article = re.sub(r'(?is)</html>.+', '</html>', article)

In general:

str_output = re.sub(regex_search_term, regex_replacement, str_input)