How to decipher :re.split(r"(\(\([^)]+\)\))" in the example
__peter__ at web.de
Thu Jul 10 18:49:28 CEST 2014
> This example is from the link:
> I have thought about it quite a while without a clue yet. I notice that it
> uses double quote ", in contrast to ' which I see more often until now.
> It looks very complicated to me. Could you simplified it to a simple
Just break it into its components.
"(...)" in the context of re.split() keeps the delimiters while just "..."
does not. Example:
>>> re.split("a+", "abbaaababa")
['', 'bb', 'b', 'b', '']
>>> re.split("(a+)", "abbaaababa")
['', 'a', 'bb', 'aaa', 'b', 'a', 'b', 'a', '']
r"\(" matches the openening parenthesis. The "(" has to be escaped because
it otherwise has a special meaning (begin group) in a regex.
"[abc]" matches a, b, or c. A leading ^ inverts the set, so "[^abc]" matches
anything but a, b, or c. Therefore "[^)]" matches anything but the closing
The complete regex then is: match two opening parens, then one or more chars
that are not closing parens, then two closing parens, and make the complete
group part of the resulting list.
PS: Note that sometimes the re.DEBUG flag may be helpful in understanding
max_repeat 1 4294967295
<_sre.SRE_Pattern object at 0x7f5740455c90>
> import re
> split_up = re.split(r"(\(\([^)]+\)\))",
> "This is a ((test)) of the ((emergency broadcasting
> ...which produces:
> ["This is a ", "((test))", " of the ", "((emergency broadcasting
> [station.))" ]
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