CODEWITHSUNDEEP
pythonregexstring
Simple runner
Simple runner

Reputation: 445

Remove only double letters sequences in word with best speed with python

Very popular task for finding/replacing double letters in a string. But exist solution, where you can make remove double letters through few steps. For example, we have string "skalallapennndraaa", and after replacing double letters we need to get in output "skalpendra". I tried solution with 

re.sub(r'([a-z])\1+', r'\1', "skalallapennndraaa")

, but this don't remove all double letters in a string(result- "skalalapendra"). If I use r'' as second parameter, I got a closely related result "skalaapendr", but I still can't find right regular expression for replacement parameter. Any ideas?

Upvotes: 0

Views: 801

Answers (1)

anubhava
anubhava

Reputation: 785761

You can use this double replacement:

>>> s = 'skalallapennndraaa'
>>> print re.sub(r'([a-z])\1', '', re.sub(r'([a-z])([a-z])\2\1', '', s))
skalpendra

([a-z])([a-z])\2\1 will remove alla type of cases and ([a-z])\1 will remove remaining double letters.

Update: Based on comments below I realize a loop based approach is best. Here it is:

>>> s = 'nballabnz'
>>> while re.search(r'([a-z])\1', s):
...     s = re.sub(r'([a-z])\1', '', s)
...
>>> print s
z

Upvotes: 2

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