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numpy.argmax() in Python

  • Difficulty Level : Easy
  • Last Updated : 31 Aug, 2021
Geek Week

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.arrange(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.arrange(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]

References : 
https://docs.scipy.org/doc/numpy-dev/reference/generated/numpy.argmax.html#numpy.argmax

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

This article is contributed by Mohit Gupta_OMG πŸ˜€. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
 

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