How to sum arrays in nested arrays?

Question

I have a nested array

array([[1,2,4], [2,5,6]])

I want to sum each array in it to get:

array([[7], [13]])

How to do that? When I do np.array([[1,2,4], [2,5,6]]) it gives

array([7, 13])

Do you know how to add a dimension to an array? np.sum(arr, axis=1)[:,None]. The keep_dims parameter is handy, but you should also be familiar with this None idiom. — hpaulj
– hpaulj, Commented Oct 10, 2021 at 23:20

Jab · Accepted Answer · 2021-10-10 22:34:02Z

3

Using sum over axis 1:

>>> a = np.array([[1,2,4], [2,5,6]])
>>> a.sum(axis=1, keepdims=True)
[[ 7]
 [13]]

Or without numpy:

>>> a = [[1,2,4], [2,5,6]]
>>> [[sum(l)] for l in a]
[[7], [13]]

answered Oct 10, 2021 at 22:21

Jab

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Comments

Agent Biscutt · Accepted Answer · 2021-10-10 22:23:38Z

0

I am not sure what the array() function is, but if its just a list, then this should work:

a=array([[1,2,4], [2,5,6]])
b=[[sum(x)] for x in a] #new list of answers

answered Oct 10, 2021 at 22:23

Agent Biscutt

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