+1 vote
in Programming Languages by (8.1k points)

How to create an empty matrix so that I can update its cells using index values.

E.g.

[[0, 0, 0],

 [0, 0, 0],

 [0, 0, 0]]

 

1 Answer

0 votes
by (15.9k points)

You can use Numpy's empty() or zeros() or ones() to declare an array or matrix of any size. empty() will put some random numbers in cells, zeros() will put 0 and ones() will put 1.

>>> import numpy as np
>>> aa=np.zeros((3,3), dtype=int)
>>> aa
array([[0, 0, 0],
       [0, 0, 0],
       [0, 0, 0]])
>>> aa[2][2]=5
>>> aa
array([[0, 0, 0],
       [0, 0, 0],
       [0, 0, 5]])

>>> bb=np.empty((3,3), dtype=int)
>>> bb
array([[       19609920,        20491424, 140256443196784],
       [140256732807088, 140256808845232, 140256808299056],
       [140256808398384, 140256807864816,              80]])
>>> cc=np.ones((3,3), dtype=int)
>>> cc
array([[1, 1, 1],
       [1, 1, 1],
       [1, 1, 1]])
>>> bb[1][0]=0
>>> bb
array([[       19609920,        20491424, 140256443196784],
       [              0, 140256808845232, 140256808299056],
       [140256808398384, 140256807864816,              80]])
>>> cc[2][0]=5
>>> cc
array([[1, 1, 1],
       [1, 1, 1],
       [5, 1, 1]])
>>>

>>> dd=np.ones((3,3,3), dtype=int)
>>> dd
array([[[1, 1, 1],
        [1, 1, 1],
        [1, 1, 1]],

       [[1, 1, 1],
        [1, 1, 1],
        [1, 1, 1]],

       [[1, 1, 1],
        [1, 1, 1],
        [1, 1, 1]]])

>>> ee=np.ones((3), dtype=int)
>>> ee
array([1, 1, 1])

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