The numpy.nanargmax() function returns indices of the max element of the array in a particular axis ignoring NaNs.
The results cannot be trusted if a slice contains only NaNs and Infs.
Syntax:
numpy.nanargmax(array, axis = None)
Parameters :
array : Input array to work on axis : [int, optional]Along a specified axis like 0 or 1
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 nanargmax() import numpy as geek # Working on 1D array array = [geek.nan, 4, 2, 3, 1] print("INPUT ARRAY 1 : \n", array) array2 = geek.array([[geek.nan, 4], [1, 3]]) # returning Indices of the max element # as per the indices ingnoring NaN print("\nIndices of max in array1 : ", geek.nanargmax(array)) # Working on 2D array print("\nINPUT ARRAY 2 : \n", array2) print("\nIndices of max in array2 : ", geek.nanargmax(array2)) print("\nIndices at axis 1 of array2 : ", geek.nanargmax(array2, axis = 1)) |
Output :
INPUT ARRAY 1 : [nan, 4, 2, 3, 1] Indices of max in array1 : 1 INPUT ARRAY 2 : [[ nan 4.] [ 1. 3.]] Indices of max in array2 : 1 Indices at axis 1 of array2 : [1 1]
Code 2: Comparing working of argmax and nanargmax
Python
# Python Program illustrating # working of nanargmax() import numpy as geek # Working on 2D array array = ( [[ 8, 13, 5, 0], [ 16, geek.nan, 5, 3], [geek.nan, 7, 15, 15], [3, 11, 4, 12]]) print("INPUT ARRAY : \n", array) # returning Indices of the max element # as per the indices ''' [[ 8 13 5 0] [ 16 2 5 3] [10 7 15 15] [ 3 11 4 12]] ^ ^ ^ ^ ''' print("\nIndices of max using argmax : ", geek.argmax(array, axis = 0)) print("\nIndices of max using nanargmax : : ", geek.nanargmax(array, axis = 0)) |
Output :
INPUT ARRAY : [[8, 13, 5, 0], [16, nan, 5, 3], [nan, 7, 15, 15], [3, 11, 4, 12]] Indices of max using argmax : [2 1 2 2] Indices of max using nanargmax : : [1 0 2 2]
Note :
These codes won’t run on online IDE’s. So please, run them on your systems to explore the working.
This article is contributed by Mohit Gupta_OMG 😀. If you likeneveropen 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 theneveropen 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.
