numpy.argmax() in Python (original) (raw)

Last Updated : 8 Mar, 2024

The numpy.argmax() function returns indices of the max element of the array in a particular axis.

Syntax :

numpy.argmax(array, axis = None, out = None)

Parameters :

array : Input array to work on axis : [int, optional]Along a specified axis like 0 or 1 out : [array optional]Provides a feature to insert output to the out array and it should be of appropriate shape and dtype

Return :

Array of indices into the array with same shape as array.shape with the dimension along axis removed.

Code 1 :

Python `

Python Program illustrating

working of argmax()

import numpy as geek

Working on 2D array

array = geek.arange(12).reshape(3, 4) print("INPUT ARRAY : \n", array)

No axis mentioned, so works on entire array

print("\nMax element : ", geek.argmax(array))

returning Indices of the max element

as per the indices

print("\nIndices of Max element : ", geek.argmax(array, axis=0)) print("\nIndices of Max element : ", geek.argmax(array, axis=1))

`

Output :

INPUT ARRAY : [[ 0 1 2 3] [ 4 5 6 7] [ 8 9 10 11]]

Max element : 11

Indices of Max element : [2 2 2 2]

Indices of Max element : [3 3 3]

Code 2 :

Python `

Python Program illustrating

working of argmax()

import numpy as geek

Working on 2D array

array = geek.random.randint(16, size=(4, 4)) print("INPUT ARRAY : \n", array)

No axis mentioned, so works on entire array

print("\nMax element : ", geek.argmax(array))

returning Indices of the max element

as per the indices

'''
[[ 0 3 8 13] [12 11 2 11] [ 5 13 8 3] [12 15 3 4]] ^ ^ ^ ^ 12 15 8 13 - element 1 3 0 0 - indices ''' print("\nIndices of Max element : ", geek.argmax(array, axis = 0))

'''
ELEMENT INDEX ->[[ 0 3 8 13] 13 3 ->[12 11 2 11] 12 0 ->[ 5 13 8 3] 13 1 ->[12 15 3 4]] 15 1

''' print("\nIndices of Max element : ", geek.argmax(array, axis = 1))

`

Output :

INPUT ARRAY : [[ 0 3 8 13] [12 11 2 11] [ 5 13 8 3] [12 15 3 4]]

Max element : 15

Indices of Max element : [1 3 0 0]

Indices of Max element : [3 0 1 1]

Code 3 :

Python `

Python Program illustrating

working of argmax()

import numpy as geek

Working on 2D array

array = geek.arange(10).reshape(2, 5) print("array : \n", array)

array[0][1] = 6 print("\narray : \n", array)

Returns max element

print("\narray : ", geek.argmax(array))

First occurrence of an max element is given

print("\nMAX ELEMENT INDICES : ", geek.argmax(array, axis = 0))

`

Output :

array : [[0 1 2 3 4] [5 6 7 8 9]]

array : [[0 6 2 3 4] [5 6 7 8 9]]

array : 9

MAX ELEMENT INDICES : [1 0 1 1 1]

Note :
These codes won’t run on online IDE’s. Please run them on your systems to explore the working.