John Salerno wrote: > So my question is, how can find all occurrences of a pattern in a > string, including overlapping matches? I figure it has something to do > with look-ahead and look-behind, but I've only gotten this far: > > import re > string = 'abababababababab' > pattern = re.compile(r'ab(?=a)') > m = pattern.findall(string) > > This matches all the 'ab' followed by an 'a', but it doesn't include the > 'a'. What I'd like to do is find all the 'aba' matches. A regular > findall() gives four results, but really there are seven. > > Is there a way to do this with just an RE pattern, or would I have to > manually add the 'a' to the end of the matches?
Yes, and no extra for loops are needed! You can define groups inside the lookahead assertion: >>> import re >>> re.findall(r'(?=(aba))', 'abababababababab') ['aba', 'aba', 'aba', 'aba', 'aba', 'aba', 'aba'] --Ben -- http://mail.python.org/mailman/listinfo/python-list
