CODEWITHSUNDEEP
pythonregex
user3116355
user3116355

Reputation: 1197

Regex pattern to avoid match certain words like customize negation

I am having a regular expression to match a particular pattern. Say, a pattern that will match all three letter words. But i want it to not match words like 'and','got' etc... What would be the best way to do it ,in Python.

My pattern is 

r'\b\w{3}\b'

I tried 

r'(\b\w{3}\b)(?!and)'

but fails.

Upvotes: 0

Views: 97

Answers (1)

Jongware
Jongware

Reputation: 22457

Regexes match left to right, and lookaheads are no exception. Your expression will match three letters that are not followed by and (which is impossible because of the \b, by the way).

Move the lookahead before the \w to make it work:

r'(\b(?!and)\w{3}\b)'

You can add more words there --

r'(\b(?!and|got|may)\w{3}\b)'

but for more non-matches it may be more effective to match all three letter words and use code to strip the result of them.

Upvotes: 4

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