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numpy.flatnonzero() in Python

  • Last Updated : 28 Nov, 2018

numpy.flatnonzero()function is used to Compute indices that are non-zero in the flattened version of arr.

Syntax : numpy.flatnonzero(arr)

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Parameters :
arr : [array_like] Input array.



Return : ndarray
Output array, containing the indices of the elements of arr.ravel() that are non-zero.

Code #1 : Working




# Python program explaining
# flatnonzero() function
  
import numpy as geek
arr = geek.arange(-3, 4)
  
print ("Input  array : ", arr)
    
out_arr = geek.flatnonzero(arr)
print ("Indices of non zero elements : ", out_arr) 

Output :

Input  array :  [-3 -2 -1  0  1  2  3]
Indices of non zero elements :  [0 1 2 4 5 6]

 
Code #2 : Using the indices of the non-zero elements as an index array.




# Python program using the indices of the non-zero 
# elements as an index array to extract these elements
  
out_arr = arr.ravel()[geek.flatnonzero(arr)]
  
print ("Output array of non-zero number: ", out_arr) 

Output :

Output array of non-zero number:  [-3 -2 -1  1  2  3]
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