RE split multiple arguments | (or) returns none python

Question

I\'m using the RE expression in python and trying to split a chunk of text by period and by exclamation mark. However when I split it, I get a \"None\" in the result

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Answer 1

it is happening because after every exclamation mark there's a space character which is returned as None here.

You can use filter to remove these None's.

>>> import re
>>> a = "This is my text...I want it to split by periods. I also want it to split \
by exclamation marks! Is that so much to ask?"

>>> filter(lambda x:x!=None, re.split('((?<=\w)\.(?!\..))|(!)',a))

['This is my text...I want it to split by periods', '.', ' I also want it to split by exclamation marks', '!', ' Is that so much to ask?']

Answer 2

Try the following:

re.split(r'((?<=\w)\.(?!\..)|!)', a)

You get the None because you have two capturing groups, and all groups are included as a part of the re.split() result.

So any time you match a . the second capture group is None, and any time you match a ! the first capture group is None.

Here is the result:

['This is my text...I want it to split by periods',
 '.',
 ' I also want it to split by exclamation marks',
 '!',
 ' Is that so much to ask?']

If you don't want to include '.' and '!' in your result, just remove the parentheses that surround the entire expression: r'(?<=\w)\.(?!\..)|!'

Answer 3

Here's a simpler expression (any period not followed or preceeded by a period) with the outer capturing group around the whole or | clause to avoid the None, not just the first part:

re.split(r'((?<!\.)\.(?!\.)|!)', a)

# Result:
# ['This is my text...I want it to split by periods', 
#  '.', 
#  ' I also want it to split by exclamation marks', 
#  '!', 
#  ' Is that so much to ask?']