Python: how to cut off sequences of more than 2 equal characters in a string

Question

I'm looking for an efficient way to chance a string such that all sequences of more than 2 equal characters are cut off after the first 2.

Some input->output examples are:

hellooooooooo -> helloo
woooohhooooo -> woohhoo

I'm currently looping over the characters, but it's a bit slow. Does anyone have another solution (regexp or something else)

EDIT: current code:

word_new = ""
        for i in range(0,len(word)-2):    
            if not word[i] == word[i+1] == word[i+2]:
                word_new = word_new+word[i]
        for i in range(len(word)-2,len(word)):
            word_new = word_new + word[i]

Answer 1

Edit: after applying helpful comments

import re

def ReplaceThreeOrMore(s):
    # pattern to look for three or more repetitions of any character, including
    # newlines.
    pattern = re.compile(r"(.)\1{2,}", re.DOTALL) 
    return pattern.sub(r"\1\1", s)

---

(original response here) Try something like this:

import re

# look for a character followed by at least one repetition of itself.
pattern = re.compile(r"(\w)\1+")

# a function to perform the substitution we need:
def repl(matchObj):
   char = matchObj.group(1)
   return "%s%s" % (char, char)

>>> pattern.sub(repl, "Foooooooooootball")
'Football'