complementary lists?

Kay Schluehr kay.schluehr at
Wed Apr 29 05:52:27 CEST 2009

On 29 Apr., 05:41, Ross <ross.j... at> 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.

z = [u for u in x if u not in y]


z = [u for u in x if u not in set(y)]

Since you are dealing with tuples and a natural order might not be
that relevant you can also set objects in the first place:

z = x - y

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