Numpy, matrix of integer list

Question

I have the next list

lst = [([0, 0, 1, 1], [0, 1, 0, 1], [0, 2, 1, 2], [1, 1, 0, 0]), ([0, 0, 1, 1], [0, 2, 1, 2], [0, 1, 0, 1], [1, 1, 0, 0])]

each set has 4 lists that contain 4 integers inside.

I need a matrix in numpy like this one, (for the first set, for example):

numpy_matrix = [ [0, 0, 1, 1] , [0, 1, 0, 1]
                [0, 2, 1, 2] , [1, 1, 0, 0] ]

notice that is a 2x2 matrix, and inside instead of saving integers is saving a list of those integers so I can do something like this:

print(numpy_array[0, 0][3]) # output: 1

I've tried this but didn't work:

np.matrix(lst[0]).reshape(2,-1)
# output:
# matrix([[0, 0, 1, 1, 0, 1, 0, 1],
#         [0, 2, 1, 2, 1, 1, 0, 0]])

Yey, now It worked, could you elaborate why the 4 is nedeed there? Please, post it as an answer so I can give your reply as correct! thanks :) — Sharki
– Sharki, Commented Oct 7, 2021 at 15:00
Look at np.array(lst).shape. It's (2,4,4), right? What shape do you want? Your focus on lst[0] makes things a bit unclear, but I think you want (2,2,2,4) — hpaulj
– hpaulj, Commented Oct 7, 2021 at 15:38

Dani Mesejo · Accepted Answer · 2021-10-07 15:11:49Z

1

If I understood correctly, you can do the following:

import numpy as np

lst = [([0, 0, 1, 1], [0, 1, 0, 1], [0, 2, 1, 2], [1, 1, 0, 0]),
       ([0, 0, 1, 1], [0, 2, 1, 2], [0, 1, 0, 1], [1, 1, 0, 0])]

arr = np.array(lst[0]).reshape(2, 2, 4)
print(arr)

Output

[[[0 0 1 1]
  [0 1 0 1]]

 [[0 2 1 2]
  [1 1 0 0]]]

The expression:

.reshape(2, 2, 4)

reshape the array to a 3-dimensional array where the length of the first dimension is 2, the second one is 2 and the last one is 4.

answered Oct 7, 2021 at 15:11

Dani Mesejo

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