How to get all indices for the maximum value in a numpy array?

Question

I have an array of numbers, and the maximum value might occurrence more than once.

How can we get a collection of indices of all the occurrences of the maximum value in the array?

For example, for the following array:

import numpy as np

a = np.array((1,2,3,2,3,2,1,3))

the result should be [2, 4, 7] (or an equivalent array or tuple).

score 11 · Accepted Answer · answered Aug 12 '11 at 10:51

11

import numpy as np

a = np.array((1,2,3,2,3,2,1,3))

occurences = np.where(a == a.max())

# occurences == array([2, 4, 7])

answered Aug 12 '11 at 10:51

eumiro

6

I'm not sure if this is true with more recent versions, but with v1.4.0, should have `occurences = np.where(a == a.max())[0]` such that you get an array rather than a tuple in occurences. – dtlussier Aug 15 '11 at 17:36

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