complementary lists?

[Mensanator]

On Apr 28, 10:41�pm, Ross <ross.j... at gmail.com> wrote:
> If I have a list x = [1,2,3,4,5,6,7,8,9] and another list that is a
> subset of x: �y = [1,4,7] , is there a quick way that I could return
> the complementary subset to y.... z=[2,3,5,6,8,9] ?
>
> The reason I ask is because I have a generator function that generates
> a list of tuples and I would like to divide this list into
> complementary lists.

>>> s = set([1,2,3,4,5,6,7,8,9])

>>> s.difference(set([1,4,7]))

set([2, 3, 5, 6, 8, 9])