CODEWITHSUNDEEP
pythonnumpy
Jasper Bernales
Jasper Bernales

Reputation: 1681

Adding Submatrix in Numpy without Loop

Let's say I got this a = np.arange(9).reshape((3,3)) I want get a numpy array of [9,12,15] which is a result of 

[0+3+6, 1+4+7, 2+5+8]

Upvotes: 4

Views: 236

Answers (2)

Chiel
Chiel

Reputation: 6194

Use the numpy.sum function and specify the axis over which you want to sum, which is 0 in your case:

import numpy as np

a = np.arange(9).reshape((3,3))
a_sum = np.sum(a, axis=0)

print a_sum

This gives you:

[ 9 12 15]

The answer of Kasramvd uses the object-oriented approach, which some people prefer:

a_sum = a.sum(axis=0)

Upvotes: 4

Kasravnd
Kasravnd

Reputation: 107337

You can usenumpy.array.sum() function by passing the axis=0:

>>> a.sum(axis=0)
array([ 9, 12, 15])

Upvotes: 5

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