Creating a matrix of matrices using numpy.array()

Question

I've been trying to create a matrix of matrices using the numpy function numpy.array() and am facing difficulties

I'm specifically trying to create the following matrix

[

 [                    [
   [ 1 ,2 ]             [ 1 , 2 ]
   [ 3 ,4 ]             [ 3 , 4 ]
 ]               ,    ]

]

[

 [                    [
   [ 1 ,2 ]             [ 1 , 2 ]
   [ 3 ,4 ]             [ 3 , 4 ]
 ]               ,    ]

]

more precisely like this one

I've tried the following line in Jupyter

x = np.array( [
        [   [ 1,2 ] ,[ 3, 4]  ] ,  [   [ 1,2 ] ,[ 3, 4]  ] ,
        [   [ 1,2 ] ,[ 3, 4]  ] ,  [   [ 1,2 ] ,[ 3, 4]  ]
])

but what it does is puts all the 2X2 matrices in row-wise form.

I'm not able to take 2( 2X2 ) matrices in row form and replicate them in columns or 2 ( 2X2 ) matrices in column form and replicate them into rows

Any idea how to create this using numpy.array() or any other approach( using numpy functions )

it seem simple but I'm finding difficulties in formulating the code. Thanks in advance.

np.array replicates the nesting of the input brackets exactly. — hpaulj
– hpaulj, Commented Mar 29, 2020 at 10:48
numpy does not dIsplay a (2,2,2,2) array like that. Don't confuse display layout with actual data shape — hpaulj
– hpaulj, Commented Mar 29, 2020 at 11:41

MeanStreet · Accepted Answer · 2020-03-29 07:52:18Z

1

>>> a = np.array([[[[1,2],[3,4]], [[1,2], [3,4]]], [[[1,2],[3,4]], [[1,2], [3,4]]]])
>>> a
array([[[[1, 2],
         [3, 4]],

        [[1, 2],
         [3, 4]]],


       [[[1, 2],
         [3, 4]],

        [[1, 2],
         [3, 4]]]])

edited Mar 29, 2020 at 7:52

answered Mar 29, 2020 at 7:41

MeanStreet

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5 Comments

hackncrack Over a year ago

yes, but i want them replicated into columns as well , a 2X2 matrix which has 2X2 matrices as elements

MeanStreet Over a year ago

So you mean a 4D matrix ? I edited the answer, let me know if it's what you're looking for

hackncrack Over a year ago

yes, a 4D matrix , a 2X2 matrix the elements of which are 2X2 matrices

hpaulj Over a year ago

The shape is (2,2,2,2).

hackncrack Over a year ago

right that's what i was looking for , took me a while to realise

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