> and I want to extract the numbers 531, 2285, ...,359. > > One thing for sure is that these numbers are the ONLY part that is > changing; all the other characters are always fixed. >
I'm not sure about what you mean by "always fixed" but I guess it means that you have n files with a fixed start and a changing ending, and m files with a fixed start and a changing ending, .... import re filenames=['ac99_124.txt', 'ac99_344.txt', 'ac99_445.txt'] numbers=[] for i in filenames: numbers.append(int(re.compile('[^_]*_(?P<number>[^.]*).txt').match(i).group('number'))) this sets numbers to: [124, 344, 445] -- http://mail.python.org/mailman/listinfo/python-list