python - Best way to find the intersection of multiple sets?

Question

I have a list of sets:

setlist = [s1,s2,s3...]

I want s1 ∩ s2 ∩ s3 ...

I can write a function to do it by performing a series of pairwise s1.intersection(s2), etc.

Is there a recommended, better, or built-in way?

Answer 1

From Python version 2.6 on you can use multiple arguments to set.intersection(), like

u = set.intersection(s1, s2, s3)

If the sets are in a list, this translates to:

u = set.intersection(*setlist)

where *a_list is list expansion

Note that set.intersection is not a static method, but this uses the functional notation to apply intersection of the first set with the rest of the list. So if the argument list is empty this will fail.