combinations of variable length nested lists

[Andrew Walkingshaw]

In article <3b6ff692.1462602 at nntp.sprynet.com>, David C. Ullrich wrote:
>Well there's an obvious "just do it" recursive version. 

Which is much nicer than the following non-recursive one, which makes
hideously many assumptions about the nature of everything
(specifically, any more than one depth of nesting in the input and it
utterly breaks):

from __future__ import nested_scopes

input = [[1,2,3],[4,5],[6,7,8,9],[10],[11,12]]

def permute(list):
    totlists = 1
    for x in xrange(len(list)): totlists *= len(list[x])
    result = [ [] for x in xrange(0, totlists) ]
    for x in xrange(0, len(list)):
        for y in xrange(0, len(list[x])):
            for z in filter(lambda a: divmod(a+y, len(list[x]))[1]==0, 
                            xrange(0, totlists)):
                result[z].append(list[x][y])
        result.sort()
    return result

if __name__ == "__main__":
    for line in permute(input):
        print repr(line)


I apologise for how vile this is. :)

This does actually work, but I'd be amazed if the sort didn't do nasty
things to performance; however, if recursion really bothers you, it's
yet another answer.

-- 
#!/usr/bin/env python
#97.110.100.114.101.119.64.108.101.120.105.99.97.108.46.111.114.103.46.117.107
import sys; print("".join([chr(int(r)) for r in open(sys.argv[0],"r").
readlines()[1][1:].split('.')])) #needs python 2; adw27 at cam.ac.uk(academic)