Python Matrix Manipulation - Square Each Element

How do I take a matrix such as: matrix = [[2,0,2],[0,2,0],[2,0,2]] and transform it to [[4,0,4],[0,4,0],[4,0,4]] where all the elements in the list become squared? I'm trying to do

Solution 1:

Using list comprehension:

>>> lis = [[2,0,2],[0,2,0],[2,0,2]]
>>> [[y**2 for y in x] for x in lis]
[[4, 0, 4], [0, 4, 0], [4, 0, 4]]

Solution 2:

List comprehensions can be nested:

sqd = [[elem*elem for elem ininner] forinnerinouter]

In this case outer would be your matrix matrix

>>>> matrix = [[2,0,2],[0,2,0],[2,0,2]]
>>>> sqd = [[elem*elem for elem in inner] for inner in matrix]
>>>> sqd
[[4, 0, 4], [0, 4, 0], [4, 0, 4]]

Solution 3:

Use numpy:

import numpy as np

matrix = [[2,0,2],[0,2,0],[2,0,2]]
np_matrix = np.array(matrix)
np_matrix**2

A list comprehension could look like this

matrix2 = [
    [e*e for e in l]
    for l in matrix
]

Solution 4:

If you mean by

matrix = [[2,0,2],[0,2,0],[2,0,2]]

a list of lists, then do the following

import numpy as np
np.square(matrix)

This gives you output as follows:

array([[4, 0, 4],
       [0, 4, 0],
       [4, 0, 4]], dtype=int32)

However, if you really mean it to be a matrix, you have to create a matrix first as follows:

X = np.matrix('2 0 2; 0 2 0;  2 0 2')

and then do the same as above, i.e.,

np.square(X)

This gives you the desired output as follows:

[[4 0 4]
 [0 4 0]
 [4 0 4]]