python list of numpy arrays to 2d array code example

Example 1: numpy generate random 2d array

import numpy as np
a=np.random.rand(3,3)
print(a)

Example 2: 2d array python initialize

>>> b = [['a']*3]*3
>>> b
[['a', 'a', 'a'], ['a', 'a', 'a'], ['a', 'a', 'a']]
>>> b[1][1]
'a'
>>> b[1][1] = 'b'
>>> b
[['a', 'b', 'a'], ['a', 'b', 'a'], ['a', 'b', 'a']]