[FIXED] how to generate combinations from multiple variables?

Issue

I have following variables;

D8 =[22, 27, 28, 30, 31, 40, 41, 42, 43, 45]
D9 = [79, 80, 90, 92, 93, 97, 98, 104, 105, 109]
D10=[61, 64, 66, 70, 72, 76, 81, 86, 87]

By using above variables, I tried to generate all the possible combinations as follows;

import itertools

stuff = [D8, D9, D10]
for L in range(0, len(stuff)+1):
    for subset in itertools.combinations(stuff, L):
        print(subset)

The result depicts as follows;

Output>>>
()
([22, 27, 28, 30, 31, 40, 41, 42, 43, 45],)
([79, 80, 90, 92, 93, 97, 98, 104, 105, 109],)
([61, 64, 66, 70, 72, 76, 81, 86, 87],)
([22, 27, 28, 30, 31, 40, 41, 42, 43, 45], [79, 80, 90, 92, 93, 97, 98, 104, 105, 109])
([22, 27, 28, 30, 31, 40, 41, 42, 43, 45], [61, 64, 66, 70, 72, 76, 81, 86, 87])
([79, 80, 90, 92, 93, 97, 98, 104, 105, 109], [61, 64, 66, 70, 72, 76, 81, 86, 87])
([22, 27, 28, 30, 31, 40, 41, 42, 43, 45], [79, 80, 90, 92, 93, 97, 98, 104, 105, 109], [61, 64, 66, 70, 72, 76, 81, 86, 87])

I want to know is there any other cleaner method to generate the above result, because in the current output I cannot flat each result into each individual outcome? Expected result should be like this?

Expected Result>>>
([])
([22, 27, 28, 30, 31, 40, 41, 42, 43, 45])
([79, 80, 90, 92, 93, 97, 98, 104, 105, 109])
([61, 64, 66, 70, 72, 76, 81, 86, 87])
([22, 27, 28, 30, 31, 40, 41, 42, 43, 45, 79, 80, 90, 92, 93, 97, 98, 104, 105, 109])
([22, 27, 28, 30, 31, 40, 41, 42, 43, 45, 61, 64, 66, 70, 72, 76, 81, 86, 87])
([79, 80, 90, 92, 93, 97, 98, 104, 105, 109, 61, 64, 66, 70, 72, 76, 81, 86, 87])
([22, 27, 28, 30, 31, 40, 41, 42, 43, 45, 79, 80, 90, 92, 93, 97, 98, 104, 105, 109, 61, 64, 66, 70, 72, 76, 81, 86, 87])

Thank you in advanced!!!

Solution

The itertools documentation contains the recipe flatten:

def flatten(list_of_lists):
    "Flatten one level of nesting"
    return chain.from_iterable(list_of_lists)

which you need to apply twice to get the desired result:

from itertools import combinations, chain

D8 = [22, 27, 28, 30, 31, 40, 41, 42, 43, 45]
D9 = [79, 80, 90, 92, 93, 97, 98, 104, 105, 109]
D10 = [61, 64, 66, 70, 72, 76, 81, 86, 87]

stuff = [D8, D9, D10]


def flatten(list_of_lists):
    """Flatten one level of nesting"""
    return chain.from_iterable(list_of_lists)


result = flatten(map(flatten, combinations(stuff, length)) for length in range(len(stuff) + 1))

for xs in result:
    print(list(xs))

producing:

[]
[22, 27, 28, 30, 31, 40, 41, 42, 43, 45]
[79, 80, 90, 92, 93, 97, 98, 104, 105, 109]
[61, 64, 66, 70, 72, 76, 81, 86, 87]
[22, 27, 28, 30, 31, 40, 41, 42, 43, 45, 79, 80, 90, 92, 93, 97, 98, 104, 105, 109]
[22, 27, 28, 30, 31, 40, 41, 42, 43, 45, 61, 64, 66, 70, 72, 76, 81, 86, 87]
[79, 80, 90, 92, 93, 97, 98, 104, 105, 109, 61, 64, 66, 70, 72, 76, 81, 86, 87]
[22, 27, 28, 30, 31, 40, 41, 42, 43, 45, 79, 80, 90, 92, 93, 97, 98, 104, 105, 109, 61, 64, 66, 70, 72, 76, 81, 86, 87]

Answered By - fanjie