Does np.argmax return the index of the first maximal element always?

Let a = np.array([1, 3, -7, ...]) be a 1D-array with several maximal elements, say at indices 10, 20 and 30. Numpy seems to return systematically 10 instead of 20 or 30, but I could not find information about this behavior in the documentation, and I could not find the implementation details in the source code. Does anybody know?

CodePudding user response：

Yes, this is actually explicited in the numpy.argmax documentation:

Notes

In case of multiple occurrences of the maximum values, the indices corresponding to the first occurrence are returned.

CodePudding user response：

No it only outputs the first occurrence but you can use np.argsort to get n top maximum:

np.argsort(your_array)[-n:] #the top n indexes

i.e.:

n=2
a = np.array([1,2,3,3,-1])
np.argsort(a)[-n:]
>array([2, 3], dtype=int64) #elements at index 2 and 3 in array a (3, 3) have the top max values