divide a ndarray by narray element-wise

Question

I have this ndarray (not matrix):

mx = np.array([[10,25,33],[3,1,5],[50,50,52]])

[[10 25 33]
 [ 3  1  5]
 [50 50 52]]

and I want to get a ndarray of shares by dividing every element by the sum of the column. So the result of this operation:

[[10/63 25/76 33/90]
 [ 3/63  1/76  5/90]
 [50/63 50/76 52/90]]

I can do

np.true_divide(mx,mx.sum(axis=0))

Are ther some build-in functions to calculate shares or stuff like that?

In what way it doesn't work? I tried the code and it does exactly what you wanted in Python3. — sophros
– sophros, Commented Feb 13, 2018 at 15:03
It returns all 0. Just discovered the np.true_divide(), so it's solved. — user9187374
– user9187374, Commented Feb 13, 2018 at 15:05
Just use mx / mx.sum(axis=0). If that does the wrong division, use from __future__ import division at the top of your file — Eric
– Eric, Commented Feb 13, 2018 at 21:24

sophros · Accepted Answer · 2018-02-13 15:06:32Z

1

The problem is related to how int behaves in division between python2 and python3. Should you start with float array it would work fine. There is also np.true_divide() that you mention in the comment.

answered Feb 13, 2018 at 15:06

sophros

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