Resizing a Matrix by summing the elements

Asked Dec 02 '19 at 17:25

Active Dec 02 '19 at 18:58

Viewed 41 times

Suppose I have a numpy array of size 4x4:

      1 1 1 1
A =   1 1 1 1
      1 1 1 1
      1 1 1 1

I want to reshape the above matrix into blocks of 2x2 shaped matrices such that the entries in this new matrix are the sums of the four quadrants of the 4x4 matrix.

B = 4 4
    4 4

I am wondering if there is a simple way to do this in NumPy. numpy.reshape() does not allow for the data to be aggregated, so I am wondering if this would be something I need to do in an iteration.

edited Dec 02 '19 at 18:58

Divakar

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asked Dec 02 '19 at 17:25

GrayLiterature

Just do: `arr.reshape((2, 4, 2)).sum(axis=1)` – Dani Mesejo Dec 02 '19 at 17:31
While this works, it's not what I need. I need to be able to add the four quadrants up as opposed to the column elements. – GrayLiterature Dec 02 '19 at 17:52
What do you mean by "add the four quadrants up"? Anyway does the duplicated link answers your question? – Dani Mesejo Dec 02 '19 at 17:53
You can imagine the 4x4 matrix being made up of 4 2x2 matricies, which is essentially dividing the 4x4 matrix into 4 quadrants. – GrayLiterature Dec 02 '19 at 17:54

Resizing a Matrix by summing the elements

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