CODEWITHSUNDEEP
python
GhostKU
GhostKU

Reputation: 2108

How to get all combination from multiple lists?

I am not sure that my question is correct but I don't know how to explain it otherwords. So I've got some lists like

a = ['11', '12']
b = ['21', '22']
c = ['31', '32']

And i need to get something like:

result = [
    ['11', '21', '31'],
    ['11', '21', '32'],
    ['11', '22', '31'],
    ['11', '22', '32'],
    ['12', '21', '31'],
    ['12', '21', '32'],
    ['12', '22', '31'],
    ['12', '22', '32']
]

Upvotes: 11

Views: 10000

Answers (5)

Raymond Pang
Raymond Pang

Reputation: 797

A solution without using any library:

def subproblem(list_a, list_b):
    c = list()
    for i, a_i in enumerate(list_a):
        for j, b_j in enumerate(list_b):
            c.append(a_i + [b_j])
    return c


def multi_lists_find_all_combination(lists):
    com = [[]]
    if len(lists) == 1:
        return lists[0]
    for i in range(0, len(lists)):
        print(i)
        com = subproblem(com, lists[i])
    return com

a = ['11', '12']
b = ['21', '22']
c = ['31', '32']

ans = multi_lists_find_all_combination([a,b,c])

Upvotes: 0

R.A.Munna
R.A.Munna

Reputation: 1709

import numpy as np    
np.array(np.meshgrid(a, b, c)).T.reshape(-1,3)

edit

import numpy as np 
len = 3 #combination array length
np.array(np.meshgrid(a, b, c)).T.reshape(-1,len)

Upvotes: 0

khelili miliana
khelili miliana

Reputation: 3822

import itertools
list(itertools.product(a,b,c))

Or using numpy

import numpy
[list(x) for x in numpy.array(numpy.meshgrid(a,b,c)).T.reshape(-1,len(a))]

Upvotes: 0

McGrady
McGrady

Reputation: 11477

You need itertools.product which returns cartesian product of input iterables.

>>> a = ['11', '12']
>>> b = ['21', '22']
>>> c = ['31', '32']
>>>
>>> from itertools import product
>>>
>>> list(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')]

And you can use a list comprehension to convert tuples to lists:

>>> [list(i) for i in 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']]

Upvotes: 8

Netwave
Netwave

Reputation: 42678

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')]

Upvotes: 5

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