CODEWITHSUNDEEP
pythonlistloops
Blue Eden
Blue Eden

Reputation: 59

Getting Every Possible combination of each list in a list of list of arbitrary length

Say I have a list of lists: beers.

speights = [1, 10]    
tui = [2, 7]    
export = [3, 9]    
beers = [speights, tui, export]

So I can only find how to get every possible combination of a list of lists which would be: (itertools.product(*beers)) but this gives me every combination including the ratings and the index of each beer aswell.

To make this more clear because I am struggling to explain this concept:

[[speights], [speights, tui], [speights, export], [speights, tui, export], 
 [tui], [tui, speights], [tui, export], [tui, speights, export]
 ..... etc.]

This is the desired output and it has to work on a list of lists of any length.

Any help would be greatly appreciated and sorry if it's been asked before because I can't seem to find this specific problem.

Upvotes: 1

Views: 70

Answers (2)

niemmi
niemmi

Reputation: 17263

You could combine permutations with chain.from_iterable:

>>> from itertools import permutations, chain
>>> beers = ['speights', 'tui', 'export']
>>> list(chain.from_iterable(permutations(beers, i) for i in xrange(1, len(beers) + 1)))
[('speights',), ('tui',), ('export',), ('speights', 'tui'), ('speights', 'export'), ('tui', 'speights'), ('tui', 'export'), ('export', 'speights'), ('export', 'tui'), ('speights', 'tui', 'export'), ('speights', 'export', 'tui'), ('tui', 'speights', 'export'), ('tui', 'export', 'speights'), ('export', 'speights', 'tui'), ('export', 'tui', 'speights')]

Upvotes: 1

Selcuk
Selcuk

Reputation: 59164

You are looking for permutations of any length. Try this:

import itertools
...
c = []
for i in range(len(beers)):
    c.extend(itertools.permutations(beers, i + 1))
print(c)

will yield

[([1, 10],), ([2, 7],), ([3, 9],), ([1, 10], [2, 7]), ([1, 10], [3, 9]),
 ([2, 7], [1, 10]), ([2, 7], [3, 9]), ([3, 9], [1, 10]), ([3, 9], [2, 7]), 
 ([1, 10], [2, 7], [3, 9]), ([1, 10], [3, 9], [2, 7]), ([2, 7], [1, 10], [3, 9]), 
 ([2, 7], [3, 9], [1, 10]), ([3, 9], [1, 10], [2, 7]), ([3, 9], [2, 7], [1, 10])]

Upvotes: 1

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