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

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?"

This is my code:

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

Note that I have this (?<=\w).(?!..) because I want it to avoid ellipses. Nevertheless, the above code spits out:

['This is my text...I want it to split by periods', '.', None, ' \
I also want it to split by exclamation marks', None, '!', \
' Is that so much to ask?']

As you can see, where a period or exclamation mark is, it has added a special “None” into my list. Why is this and how do I get rid of it?

Answer 1

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)\.(?!\..)|!'