How to convert list of tuple to an array

Question

new = zero(rows_A,cols_B)
for i in range(rows_A):
    for j in range(cols_B):     
        new[i][j] += np.sum(A[i] * B[:,j])

If I'm using this form of array [[0, 0, 0], [0, 1, 0], [0, 2, 1]] in B it is giving me an error

TypeError: list indices must be integers, not tuple

but if I'm using same array B , in place of A , it's working well.

I am getting this type of return array

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

so i want to convert it into this form

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

Answer 1

numpy.asarray will do that.

import numpy as np

B = np.asarray([[0, 0, 0], [0, 1, 0], [0, 2, 1]])

This produces

array([[0, 0, 0],
       [0, 1, 0],
       [0, 2, 1]])

which can be indexed with [:, j] .

Also, it looks like you're trying to do a matrix product. You can do the same thing with just one line of code using np.dot :

new = np.dot(A, B)

Answer 2

It appears that B is a list. You can't index it as B[:,i] -- Which is implcitly passed to __getitem__ as (slice(None,None,None),i) -- ie a tuple.

You could convert B to a numpy array first ( B = np.array(B) ) and then go from there ...