Lars Woetmann wrote: > I have a list I filter using another list and I would like > this to be as fast as possible > right now I do like this: > > [x for x in list1 if x not in list2] > > i tried using the method filter: > > filter(lambda x: x not in list2, list1) > > but it didn't make much difference, because of lambda I guess > is there any way I can speed this up
If you use a reasonably new python version, you could use sets: #v+ >>> a = set(range(10)) >>> a set([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]) >>> b = set(range(5, 15)) >>> b set([5, 6, 7, 8, 9, 10, 11, 12, 13, 14]) >>> a.difference(b) set([0, 1, 2, 3, 4]) >>> a-b set([0, 1, 2, 3, 4]) >>> list(a-b) [0, 1, 2, 3, 4] >>> #v- Cheers, -- Klaus Alexander Seistrup SubZeroNet, Copenhagen, Denmark http://magnetic-ink.dk/ -- http://mail.python.org/mailman/listinfo/python-list
