Question

I’ve a dictionary with a (x,y) key, where (x,y) means the same as (y,x), How should I do this ?

I can do:

>>> d = {(1,2): "foo"}
>>> i = d.get(2,1)
>>> if i is None:
...     i = d.get((1,2))
...
>>> i
'foo'

Is there a better way of doing this, so d.get((2,1)) would match the key (1,2) directly ?
ideally i’d want to insert e.g. (2,1) and not have it be distinct from the (1,2) key as well.

Answer 1

Use frozensets rather than tuples.

d = {frozenset((1,2)): "foo"}
print d.get(frozenset((2,1)))