python combinations function

1import itertools
2
3a = [1, 2, 3]
4n = 3
5
6perm_iterator = itertools.permutations(a, n)
7
8for item in perm_iterator:
9    print(item)

1def combinations(iterable, r):
2    pool = tuple(iterable)
3    n = len(pool)
4    for indices in permutations(range(n), r):
5        if sorted(indices) == list(indices):
6            yield tuple(pool[i] for i in indices)