All possible combinations of arrays in python-CodePudding

I have a problem finding all combinations of a 2D array. Let's suggest I have an array as follwoing:

[  
[1,2],  
[3,4],  
[5,6]  
]

Now I need to get all possible combninations such as

[  
[1,3,5],  
[1,3,6],  
[1,4,5],  
[1,4,6],  
[2,3,5],  
[2,3,6],  
[2,4,5],  
[2,4,6]  
]

I've managed to get it with numpy and meshgrids with single arrays:

import numpy as np
array_1 = np.array([1,2])
array_2 = np.array([3,4])
array_3 = np.array([5,6])

combination = np.array(np.meshgrid(array_1, array_2, array_3)).T.reshape(-1,3)

But with a 2D array I cant't get it to work.

import numpy as np
multi = [np.array([1,2]), np.array([3,4]), np.array([5,6])]
combination = np.array(np.meshgrid(multi)).T.reshape(-1,len(multi))

This doesn't give me the expected result but only:

[  
[1,2,3],  
[4,5,6]  
]

Is there any way to get this working correctly?

CodePudding user response：

You can use the itertools package in the standard library. itertools.product generate all combinations that you wish.

import itertools
arrays = [
  [1,2],
  [3,4],
  [5,6]  
]  
list(itertools.product(*arrays))
#[(1, 3, 5),
# (1, 3, 6),
# (1, 4, 5),
# (1, 4, 6),
# (2, 3, 5),
# (2, 3, 6),
# (2, 4, 5),
# (2, 4, 6)]

If you prefer lists to tuples, you can do the following:

list(map(list, itertools.product(*arrays)))
#[[1, 3, 5],
# [1, 3, 6],
# [1, 4, 5],
# [1, 4, 6],
# [2, 3, 5],
# [2, 3, 6],
# [2, 4, 5],
# [2, 4, 6]]