Question

Using Python and regex I am trying to find words in a piece of text that start with a capital letter but are not at the start of a sentence.

The best way I can think of is to check that the word is not preceded by a full stop then a space. I am pretty sure that I need to use negative lookbehind. This is what I have so far, it will run but always returns nothing:

(?<!\.\s)\b[A-Z][a-z]*\b

I think the problem might be with the use of [A-Z][a-z]* inside the word boundary \b but I am really not sure.

Thanks for the help.

Answer 1

Your regex appears to work:

In [6]: import re

In [7]: re.findall(r'(?<!\.\s)\b[A-Z][a-z]*\b', 'lookbehind. This is what I have')
Out[7]: ['I']

Make sure you’re using a raw string (r'...') when specifying the regex.

If you have some specific inputs on which the regex doesn’t work, please add them to your question.