Negation in regular expressions

Paddy paddy3118 at netscape.net
Fri Sep 8 06:01:35 CEST 2006


George Sakkis wrote:
> It's always striked me as odd that you can express negation of a single
> character in regexps, but not any more complex expression. Is there a
> general way around this shortcoming ? Here's an example to illustrate a
> use case:
>
> >>> import re
> # split with '@' as delimiter
> >>> [g.group() for g in re.finditer('[^@]+', 'This @ is a @ test ')]
> ['This ', ' is a ', ' test ']
>
> Is it possible to use finditer to split the string if the delimiter was
> more than one char long (say 'XYZ') ? [yes, I'm aware of re.split, but
> that's not the point; this is just an example. Besides re.split returns
> a list, not an iterator]
>
> George

If your wiling to use groups then the following will split

>>> [g.group(1) for g in re.finditer(r'(.+?)(?:@#|$)', 'This @# is a @# test ')]
['This ', ' is a ', ' test ']

- Paddy.




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