Regular expression: match start or whitespace

Question

Can a regular expression match whitespace or the start of a string?

I\'m trying to replace currency the abbreviation GBP with a £ symbol. I

Answer 1

Use the OR "|" operator:

>>> re.sub(r'(^|\W)GBP([\W\d])', u'\g<1>£\g<2>', text)
u'\xa3 5 Off when you spend \xa375.00'

Answer 2

Yes, why not?

re.sub(u'^\W*GBP...

matches the start of the string, 0 or more whitespaces, then GBP...

edit: Oh, I think you want alternation, use the |:

re.sub(u'(^|\W)GBP...