Question

Suppose I have a set {a, b, c, d}. I want to create a “path” from it, which is a generator that yields (a, b), then (b, c), then (c, d) (of course set is unordered, so any other path through the elements is acceptable).

What is the best way to do this?

Answer 1

Here’s an example using the pairwise() recipe from http://docs.python.org/3/library/itertools.html#itertools-recipes

>>> from itertools import tee
>>> def pairwise(iterable):
...     "s -> (s0,s1), (s1,s2), (s2, s3), ..."
...     a, b = tee(iterable)
...     next(b, None)
...     return zip(a, b)
...
>>> for pair in pairwise({1, 2, 3, 4}):
...     print(pair)
...
(1, 2)
(2, 3)
(3, 4)