Python merging two lists with all possible permutations

Question

I\'m trying to figure out the best way to merge two lists into all possible combinations. So, if I start with two lists like this:

list1 = [1, 2]
list2 = [3,         


        

Answer 1

Try this:

combos=[]
for i in list1:
      for j in list2:
          combos.append([i,j])
print combos

Answer 2

The accepted answer can be simplified to

a = [1, 2, 3]
b = [4, 5, 6]
[list(zip(a, p)) for p in permutations(b)]

(The list() call can be omitted in Python 2)

Answer 3

Try to use list generator to create the nested lists:

>>> [[[x,y] for x in list1] for y in list2]
[[[1, 3], [2, 3]], [[1, 4], [2, 4]]]
>>>

Or, if you want one-line list, just delete brackets:

>>> [[x,y] for x in list1 for y in list2]
[[1, 3], [1, 4], [2, 3], [2, 4]]

Answer 4

As @pacholik s answer does not cover lists of different length, here is my solution, using a list comprehension with two variables:

first_list = [1, 2, 3]
second_list = ['a', 'b']

combinations = [(a,b) for a in first_list for b in second_list]

The output looks like this:

[(1, 'a'), (1, 'b'), (2, 'a'), (2, 'b'), (3, 'a'), (3, 'b')]

Answer 5

You can create a list by constructing all the permutations of two list members with this, containing the list combinations.

lst1 = [1,2]
lst2 = [3,4]

#lst = [[j,k] for j in lst1 for k in lst2] # [[1,3],[1,4],[2,3],[2,4]]
lst = [[[j,k] for j in lst1] for k in lst2] # [[[1,3],[2,3]],[[1,4],[2,4]]]
print lst

Answer 6

repeat the first list, permutate the second and zip it all together

>>> from itertools import permutations, repeat
>>> a = [1, 2, 3]
>>> b = [4, 5, 6]
>>> list(list(zip(r, p)) for (r, p) in zip(repeat(a), permutations(b)))
[[(1, 4), (2, 5), (3, 6)],
 [(1, 4), (2, 6), (3, 5)],
 [(1, 5), (2, 4), (3, 6)],
 [(1, 5), (2, 6), (3, 4)],
 [(1, 6), (2, 4), (3, 5)],
 [(1, 6), (2, 5), (3, 4)]]

EDIT: As Peter Otten noted, the inner zip and the repeat are superfluous.

[list(zip(a, p)) for p in permutations(b)]