Summing elements of numpy array in Python

Question

I have an numpy array

>>> clf_prob.dtype()

array([[ 0.05811791,  0.06526527,  0.06024136, ...,  0.06972481],
       [ 0.06093686,  0.06357167,  0.06462331, ...,  0.06999094],
       [ 0.08188396,  0.08504034,  0.0820972 , ...,  0.08487802],
       [ 0.05197106,  0.0786195 ,  0.15669477, ...,  0.0893244]])

I'm trying to add elements of these arrays such that my output would be:

[[0.05811791 + 0.06526527 + 0.06024136 +...+ 0.06972481],
[0.06093686 + 0.06357167 + 0.06462331 +...+0.06999094],
[0.08188396 + 0.08504034 + 0.0820972 + ...+  0.08487802],
[0.05197106 + 0.0786195  + 0.15669477+ ...+ 0.0893244]]

I tried doing

sum(map(sum, clf_prob))

This doesn't gives me desired output. Any suggestion?

np.sum(clf_prob, axis=1) (or try axis=0 if you don't like that!). Sometimes the keepdims parameter is handy - try it. — hpaulj
– hpaulj, Commented May 30, 2017 at 6:13
What is the desired output? Maybe use a smaller array so you can show all the data and the expected output. — Daniel F
– Daniel F, Commented May 30, 2017 at 6:31
clf_prob=array([[2,3],[3,1],[4,3]]) ............ desired output ([5],[4],[7]) — Andre_k
– Andre_k, Commented May 30, 2017 at 6:34

Mathias711 · Accepted Answer · 2017-05-30 06:13:08Z

2

You can do

clf_prob.sum(axis=1)

This will take the sum over a certain axis, in this case rows.

answered May 30, 2017 at 6:13

Mathias711

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Isdj · Accepted Answer · 2017-05-30 06:17:07Z

0

numpy.sum() over your intended axis (1) should do the job in your case

edited May 30, 2017 at 6:17

answered May 30, 2017 at 6:13

Isdj

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2 Comments

Eliethesaiyan Over a year ago

this will result in one number which is sum of all elements,specifying axis=1 gives a columns wise sums,axis=0 row wise

Isdj Over a year ago

@Eliethesaiyan I meant he should look at the way numpy sum works.. sorry

Code Pope · Accepted Answer · 2019-03-20 18:33:36Z

0

Another probability is to use ufunc of numpy:
np.sum.reduce(clf_prob)
which will give the sum over the first axis. You can also use the axis parameter to sum over another axis.

answered Mar 20, 2019 at 18:33

Code Pope

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