How to get index of all maximum values in an array

Question

In the following array there are two maximum values 5 and 5. np.argmax command returns the index of first maximum value. But I want to get the index of all maximum values in array using np.argmax. How I can do that?

`a= np.array([1,2,5,5,0,3])
b= np.argmax(a)
print(b)`

Sianur · Accepted Answer · 2018-06-30 04:31:45Z

2

You can use np.where() as suggested here:

a = np.array([1,2,5,5,0,3])
x = np.max(a)
b = np.where(a == x)[0]
print(b)

answered Jun 30, 2018 at 4:31

Sianur

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4 Comments

python Over a year ago

After applying condition a==x what is the purpose of [0]? Documentation says if condition is true generate x otherwise y

Sianur Over a year ago

This is another use: "If only condition is given, return the tuple condition.nonzero(), the indices where condition is True". You need the first element of the tuple.

python Over a year ago

sorry i didn't get your point. Can you please explain what [0] stands for? Is it stand for row?

Sianur Over a year ago

b = np.where(a == x) yields (array([2, 3]),). Therefore, b[0] is array([2, 3]) that you need.

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