python: getting all pairs of values from list

Question

I'd like a tuple of each pair of values from a list, e.g.

[1,2,3,4]

Would yield:

(1,2)
(1,3)
(1,4)
(2,3)
(2,4)
(3,4)

This seems very one-line recipe ish but I can't quite get it to work.

Answer 1

That is actually the combinations of 2 elements from your list. Use itertools.combinations this way:

>>> your_list = [1,2,3,4]
>>> from itertools import combinations
>>> list(combinations(your_list,2))
# [(1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4)]

If you need all pairs, use itertools.product

Or, you can use simple list-comprehension:

>>> your_list = [1,2,3,4]
>>> [(your_list[i], your_list[j]) for i in range(len(your_list)) for j in range(i+1,len(your_list))]
# [(1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4)]