Python Generating All Nondecreasing Sequences

I am having trouble finding a way to do this in a Pythonic way. I assume I can use itertools somehow because I've done something similar before but can't remember what I did. I am

Solution 1:

You can do this using itertools.combinations_with_replacement:

>>>L, N = 3,3>>>cc = combinations_with_replacement(range(1, N+1), L)>>>for c in cc: print(c)
(1, 1, 1)
(1, 1, 2)
(1, 1, 3)
(1, 2, 2)
(1, 2, 3)
(1, 3, 3)
(2, 2, 2)
(2, 2, 3)
(2, 3, 3)
(3, 3, 3)

This works because c_w_r preserves the order of the input, and since we're passing a nondecreasing sequence in, we only get nondecreasing tuples out.

(It's easy to convert to lists if you really need those as opposed to tuples.)