python regular expression help

[fokuslee]

Hi i am trying to match certain file names
i want to match things with few digits appeneded to the end preceded by underscore
such as file_1 and file_12
I do not want to match file1 or file2...
my take would be
import re
m = re.match('$_/d+','blah_12')
but m always return None
what did i do wrong?
thanks
:popcorn:

[Arndt]

Hi i am trying to match certain file names
i want to match things with few digits appeneded to the end preceded by underscore
such as file_1 and file_12
I do not want to match file1 or file2...
my take would be
import re
m = re.match('$_/d+','blah_12')
but m always return None
what did i do wrong?
thanks
:popcorn:

What are the $ and / doing there?

[kostkon]

Just a tip: install and try kodos (http://packages.ubuntu.com/maverick/kodos). It will help you to easily test and debug you python reg exps.

[fokuslee]

sorry for my sloppyness it should be a \
i actually have it like this

>>> import re
>>> m = re.match('$_\d+','blah_12')
>>> print m
None

\d means [0-9]
$ means i only want to see the match at the end
so file_1_stuff will not match

at least that is my understanding from the python docs online

[kurum!]

With Ruby, but similar regex in Python.


>> filename="file_12"
=> "file_12"
>> filename.match(/^.*_\d+$/)
=> #<MatchData "file_12">

[fokuslee]

ok i need to use re.search() not re.match
match will only look at begining of string
need to read docs mroe carefully
thanks

[Arndt]

sorry for my sloppyness it should be a \
i actually have it like this

>>> import re
>>> m = re.match('$_\d+','blah_12')
>>> print m
None

\d means [0-9]
$ means i only want to see the match at the end
so file_1_stuff will not match

at least that is my understanding from the python docs online

The $ needs to be at the end for it to work that way. I don't know whether $ has any useful function in some other position.

It starts matching at the beginning, so you need to match what comes before the interesting part:


re.match('.*_\d+$','abc_56')

or use re.search.