How to count distinct (x,y) pairs from a set of 3 dimensional tuples

Question

I have a set which contains elements like

(1,2,"r"), (1,2,"d"), (1,3,"p")

I am only interested in the number of distinct (x,y) pairs like in the above it will be 2. How do I
calculate that using python?

Answer 1

Sounds like a one-liner will suffice (supposing your set is a list of tuples , referenced by variable name l ):

l = [YOUR LIST OF TUPLES]
len(set([t[:2] for t in l]))

NB : the above treats the pair (x,y) as distinct from (y,x) ; if (x,y) and (y,x) are intended to be treated as indistinct, then use:

len(set([frozenset(t[:2]) for t in l]))