Python regex: split by repeated punctuation marks

Question

How????are!!!you

I'd like to split the string into ['How','are','you'] .

I've tried the following regex:

\?*|\!*

which does not work. However, the following regex works:

\?+|\!+

Anyone explain this to me?

Answer 1

>>> re.split(r'[?!]*', 'How????are!!!you')
['How', 'are', 'you']

As for why \\?*|\\!* doesn't work, just look at what re.findall finds:

>>> re.findall(r'\?*|\!*', 'How????are!!!you')
['', '', '', '????', '', '', '', '', '', '', '', '', '', '']

The alternation always takes the first branch if possible. re.split tries to only split by nonempty matches, so you end up splitting by ? but not ! (since \\?* will match any empty string, \\!* will never match in a non-overlapping fashion).