Doing both regex match and assignment within a If loop?
Peter Otten
__peter__ at web.de
Fri Mar 29 04:27:46 EDT 2013
Victor Hooi wrote:
> Hi,
>
> I have logline that I need to test against multiple regexes. E.g.:
>
> import re
>
> expression1 = re.compile(r'....')
> expression2 = re.compile(r'....')
>
> with open('log.txt') as f:
> for line in f:
> if expression1.match(line):
> # Do something - extract fields from line.
> elif expression2.match(line):
> # Do something else - extract fields from line.
> else:
> # Oh noes! Raise exception.
>
> However, in the "Do something" section - I need access to the match object
> itself, so that I can strip out certain fields from the line.
>
> Is it possible to somehow test for a match, as well as do assignment of
> the re match object to a variable?
>
> if expression1.match(line) = results:
> results.groupsdict()...
>
> Obviously the above won't work - however, is there a Pythonic way to
> tackle this?
>
> What I'm trying to avoid is this:
>
> if expression1.match(line):
> results = expression1.match(line)
>
> which I assume would call the regex match against the line twice - and
> when I'm dealing with a huge amount of log lines, slow things down.
(1)
for line in f:
match = expression1.match(line)
if match:
# ...
continue
match = expression2.match(line)
if match:
# ...
continue
raise NothingMatches
(2)
import re
class Matcher:
def __call__(self, expr, line):
result = self.match = expr.match(line)
return result
def __getattr__(self, name):
return getattr(self.match, name)
match = Matcher()
for line in f:
if match(expression1, line):
print(match.groupdict())
elif match(expression2, line):
print(match.group(1))
else:
raise NothingMatches
More information about the Python-list
mailing list