[Tutor] regex grouping/capturing

[Andreas Perstinger]

On 13.06.2013 17:09, Albert-Jan Roskam wrote:
> I have a string of the form "required optional3 optional2 optional1
> optional3" ('optional' may be any kind of string, so it's not simply
> 'optional\d+'.
> I would like to use a regex so I can distinguish groups. Desired
> outcome: ('required', 'optional3', 'optional2', 'optional1',
> 'optional3'). Below is  a fragment of the many things I have tried.
[SNIP]
> How can I make this work?

If you really want to use a regex:
 >>> import re
 >>> s = "required optional3 optional2 optional1 optional3"
 >>> s2 = "required optional1 optional2 optional3"
 >>> pattern = "required|optional1|optional2|optional3"
 >>> re.findall(pattern, s)
['required', 'optional3', 'optional2', 'optional1', 'optional3']
 >>> re.findall(pattern, s2)
['required', 'optional1', 'optional2', 'optional3']

But why not simply:
 >>> s.split()
['required', 'optional3', 'optional2', 'optional1', 'optional3']
 >>> s2.split()
['required', 'optional1', 'optional2', 'optional3']

Bye, Andreas