You could use re.finditer to find the longest match, and then replace it manually by hand (via string slicing).
(a match is the longest if (m.end() - m.start()) is the largest -- so, max(re.finditer(...), key=lambda m: (m.end() = m.start())) -- Devin P.S. does anyone else get bothered by how it's slice.start and slice.stop, but match.start() and match.end() ? On Fri, Dec 16, 2011 at 11:49 AM, John Gordon <gor...@panix.com> wrote: > According to the documentation on re.sub(), it replaces the leftmost > matching pattern. > > However, I want to replace the *longest* matching pattern, which is > not necessarily the leftmost match. Any suggestions? > > I'm working with IPv6 CIDR strings, and I want to replace the longest > match of "(0000:|0000$)+" with ":". But when I use re.sub() it replaces > the leftmost match, even if there is a longer match later in the string. > > I'm also looking for a regexp that will remove leading zeroes in each > four-digit group, but will leave a single zero if the group was all > zeroes. > > Thanks! > > -- > John Gordon A is for Amy, who fell down the stairs > gor...@panix.com B is for Basil, assaulted by bears > -- Edward Gorey, "The Gashlycrumb Tinies" > > -- > http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
