all possible combinations

[Rocco Moretti]

rbt wrote:
> Say I have a list that has 3 letters in it:
> 
> ['a', 'b', 'c']
> 
> I want to print all the possible 4 digit combinations of those 3
> letters:

When I have occasion to do an iteration of iterations, I either use 
recursion (already posted) or use an accumulator type loop:

items = ['a','b','c']
accume = [[],]

for pos in range(4):
   old_accume, accume = accume, []
   for comb in old_accume:
     for item in items:
       accume.append(comb + [item])

accume = [''.join(x) for x in accume]
print accume

['aaaa', 'aaab', 'aaac', 'aaba', 'aabb', 'aabc', 'aaca', 'aacb', 'aacc', 
'abaa', 'abab', 'abac', 'abba', 'abbb', 'abbc', 'abca', 'abcb', 'abcc', 
'acaa', 'acab', 'acac', 'acba', 'acbb', 'acbc', 'acca', 'accb', 'accc', 
'baaa', 'baab', 'baac', 'baba', 'babb', 'babc', 'baca', 'bacb', 'bacc', 
'bbaa', 'bbab', 'bbac', 'bbba', 'bbbb', 'bbbc', 'bbca', 'bbcb', 'bbcc', 
'bcaa', 'bcab', 'bcac', 'bcba', 'bcbb', 'bcbc', 'bcca', 'bccb', 'bccc', 
'caaa', 'caab', 'caac', 'caba', 'cabb', 'cabc', 'caca', 'cacb', 'cacc', 
'cbaa', 'cbab', 'cbac', 'cbba', 'cbbb', 'cbbc', 'cbca', 'cbcb', 'cbcc', 
'ccaa', 'ccab', 'ccac', 'ccba', 'ccbb', 'ccbc', 'ccca', 'cccb', 'cccc']

Optimize as you see fit.