CODEWITHSUNDEEP
python
user3378649
user3378649

Reputation: 5354

Make all possible combinations of list elements - using python

I am trying to make all the possible combinations of a list. like: 

l= [1,4,6,8,11,13]

combL = [ [1],[4],[6],[8],[11],[13],[1,4], ..  ]

I tried to use 

itertools.combinations(l, len(l))

but it didn't work out. Any function on Python that do that ?

Upvotes: 0

Views: 230

Answers (3)

M4rtini
M4rtini

Reputation: 13539

as a list: 

[i for j in xrange(len(l)) for i in itertools.combinations(l, j+1)]

or as a generator: 

(i for j in xrange(len(l)) for i in itertools.combinations(l, j+1))

Upvotes: 1

Anish Shah
Anish Shah

Reputation: 8159

res = []
for L in range(0, len(l)+1):
    for subset in itertools.combinations(l, L):
        res.append(list(subset))

Output:

[[], [1], [4], [6], [8], [11], [13], [1, 4], [1, 6], [1, 8], [1, 11], [1, 13], [4, 6], [4, 8], [4, 11],....

Upvotes: 0

thefourtheye
thefourtheye

Reputation: 239433

from itertools import combinations

def get_all_combinations(input_list):
    for i in xrange(len(input_list)):
        for item in combinations(input_list, r = i + 1):
            yield list(item)    

input_list = [1,4,6,8,11,13]
for item in get_all_combinations(input_list):
    print item

We have created a generator, so it is efficient as we don't have to store the entire combinations in memory. It is important for a combinations generator, because, often the number of combinations is very big.

But if you want to get all the combinations as list, then you can do

list(get_all_combinations(input_list))
# [[1], [4], [6], [8], [11], [13], [1, 4], [1, 6], [1, 8], [1, 11], [1, 13],..]

Upvotes: 5

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