krumpelstiltskin - 7 months ago 48

Python Question

I often find myself wanting to test the intersection of two sets without using the result of the intersections.

`set1 = set([1,2])`

set2 = set([2,3])

if(set1 & set2):

print("Non-empty intersection")

else:

print("Empty intersection")

The problem is that a new set is created to do this test which can be inefficient.

Is there a short way to do this without explicitly writing it out (as in the following)?

`if(any(x in set2 for x in set1)):`

print("Non-empty intersection")

else:

print("Empty intersection")

Answer

You are looking for `set.isdisjoint()`

, as sets are disjoint if and only if they have an empty intersection.

```
>>> set1 = set([1,2])
>>> set2 = set([2,3])
>>> set1.isdisjoint(set2)
False
```