Python set Union and set Intersection operate differently?

Question

I\'m doing some set operations in Python, and I noticed something odd..

>> set([1,2,3]) | set([2,3,4])
set([1, 2, 3, 4])
>> set().union(*[[1,2,3], [2         


        

Answer 1

convert the list to set first

>>> set.intersection(*[set([1,2,3]), set([2,3,4])])
set([2, 3])

For multiple lists you can just use,

>>> set.intersection(*[set([1,2,3]), set([2,3,4]), set([5,3,4])])
set([3])