Python regex to match begin of string or whitespace

Question

I have the following string

'abc[123]defgh ijk[456]lm no[78] pq'

And I would like to extract all parts which are either between the begin of the string and [ or between whitespace and [. For the given string, these are the parts 'abc', 'ijk', and 'no'.

I have the following expression

exp = re.compile(r'\s(.*?)\[')

But I cannot figure out how to add the beginning of the string as an optional expression. How do I have to write the expression to cover both cases?

p.s.w.g · Accepted Answer · 2014-01-19 19:09:42Z

7

Try this pattern:

(?:^|\s)(.*?)\[

The start anchor (^) matches the beginning of the string (or line in MULTILINE mode).

answered Jan 19, 2014 at 19:09

p.s.w.g

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1 Comment

stefangachter Over a year ago

Thanks, this works, and after having a look at the documentation, I understand the syntax as well :-)

Ron Rosenfeld · Accepted Answer · 2014-01-19 20:58:42Z

1

Another: after finding the starting character, look for everything that is NOT a [ and ensure it is followed by a [

(?:^|\s)([^\[]+)(?=\[)

edited Jan 19, 2014 at 20:58

answered Jan 19, 2014 at 19:26

Ron Rosenfeld

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