On 2015-04-08 15:28, Peter Otten wrote:
Mattias Ugelvik wrote:
Example: re.match('(?P<first>a?)(?P<second>b?)', '')
How can I find out that the group 'first' correlates to the positional
regex group 1? I need to know this to resolve crucial ambiguities in a
string manipulation tool I'm making. Looking at spans, as the example
above illustrates, won't do the job.
I can't see a way to do this through the documented interface (at
least not in the `re` module?).
Compile and match in two separate steps:
import re
r = re.compile('(?P<first>a?)(?P<second>b?)')
Find the groups' positions:
r.groupindex
{'second': 2, 'first': 1}
Find the matching substrings:
r.match("a").groupdict()
{'second': '', 'first': 'a'}
https://docs.python.org/2.7/library/re.html#re.RegexObject.groupindex
The match object has an attribute 're' that's the compiled regex:
>>> m = re.match('(?P<first>a?)(?P<second>b?)', '')
>>> m.re.groupindex
{'first': 1, 'second': 2}
--
https://mail.python.org/mailman/listinfo/python-list
