All Combinations of a List of Lists

All combinations of a list of lists

you need itertools.product:

>>> import itertools
>>> a = [[1,2,3],[4,5,6],[7,8,9,10]]
>>> list(itertools.product(*a))
[(1, 4, 7), (1, 4, 8), (1, 4, 9), (1, 4, 10), (1, 5, 7), (1, 5, 8), (1, 5, 9), (1, 5, 10), (1, 6, 7), (1, 6, 8), (1, 6, 9), (1, 6, 10), (2, 4, 7), (2, 4, 8), (2, 4, 9), (2, 4, 10), (2, 5, 7), (2, 5, 8), (2, 5, 9), (2, 5, 10), (2, 6, 7), (2, 6, 8), (2, 6, 9), (2, 6, 10), (3, 4, 7), (3, 4, 8), (3, 4, 9), (3, 4, 10), (3, 5, 7), (3, 5, 8), (3, 5, 9), (3, 5, 10), (3, 6, 7), (3, 6, 8), (3, 6, 9), (3, 6, 10)]

How to get all combination from multiple lists?

User itertools, combinations:

import itertools
a = ['11', '12']
b = ['21', '22']
c = ['31', '32']
list(itertools.combinations(itertools.chain(a,b,c), 3))
[('11', '12', '21'), ('11', '12', '22'), ('11', '12', '31'), ('11', '12', '32'), ('11', '21', '22'), ('11', '21', '31'), ('11', '21', '32'), ('11', '22', '31'), ('11', '22', '32'), ('11', '31', '32'), ('12', '21', '22'), ('12', '21', '31'), ('12', '21', '32'), ('12', '22', '31'), ('12', '22', '32'), ('12', '31', '32'), ('21', '22', '31'), ('21', '22', '32'), ('21', '31', '32'), ('22', '31', '32')]

or product:

list(itertools.product(a,b,c))
[('11', '21', '31'), ('11', '21', '32'), ('11', '22', '31'), ('11', '22', '32'), ('12', '21', '31'), ('12', '21', '32'), ('12', '22', '31'), ('12', '22', '32')]

How to create all possible combinations of a list which has lists inside of it?

Possible solution is the following:

from itertools import combinations

lst = [['Macau', 'United Kingdom', 'India'], ['United States', 'China'],  ['China', 'Australia']]

print([list(combinations(group, 2)) for group in lst])

Returns

[[('Macau', 'United Kingdom'),
  ('Macau', 'India'),
  ('United Kingdom', 'India')],
 [('United States', 'China')],
 [('China', 'Australia')]]

How to generate combinations of elements of different lists?

As you asked for a solution without itertools, this one is a recursive function that takes a list of any length and does the combination you need:

def combine(elems):
    if len(elems) == 0:
        return [[]]
    result = []    
    subcombinations =  combine(elems[1:])
    for x in elems[0]:
        for y in subcombinations:
            result.append([x, *y])
    return result

Or a much shorter version

def combine(elems):
    if len(elems) == 0:
        return [[]]
    return [[x, *y] for x in elems[0] for y in combine(elems[1:])]

Python all combinations of a list of lists

You can use itertools.chain.from_iterable to flatten the tuple of lists into a list. Example -

import itertools
input = [['a','b'],['c','d'],['e','f']]
combs = []
for i in xrange(1, len(input)+1):
    els = [list(itertools.chain.from_iterable(x)) for x in itertools.combinations(input, i)]
    combs.extend(els)

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Demo -

>>> import itertools
>>> input = [['a','b'],['c','d'],['e','f']]
>>> combs = []
>>> for i in range(1, len(input)+1):
...     els = [list(itertools.chain.from_iterable(x)) for x in itertools.combinations(input, i)]
...     combs.extend(els)
...
>>> import pprint
>>> pprint.pprint(combs)
[['a', 'b'],
 ['c', 'd'],
 ['e', 'f'],
 ['a', 'b', 'c', 'd'],
 ['a', 'b', 'e', 'f'],
 ['c', 'd', 'e', 'f'],
 ['a', 'b', 'c', 'd', 'e', 'f']]

Get all possible combinations from a list of lists by picking one item from each list

Use itertools.product:

>>> l = [[1,2],[3],[4,5,6],[7],[8,9]]
>>> from itertools import product
>>> list(product(*l))
[(1, 3, 4, 7, 8), (1, 3, 4, 7, 9), (1, 3, 5, 7, 8), (1, 3, 5, 7, 9), (1, 3, 6, 7, 8), (1, 3, 6, 7, 9), (2, 3, 4, 7, 8), (2, 3, 4, 7, 9), (2, 3, 5, 7, 8), (2, 3, 5, 7, 9), (2, 3, 6, 7, 8), (2, 3, 6, 7, 9)]

all combination in list of lists without duplicates in python

1) itertools.product

 all_combinations = itertools.product(elements)

2) filter with lambda

filtered_combinations = filter(lambda x: len(x) != len(set(x)), all_combinations)

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