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numpy.isinf() in Python

  • Difficulty Level : Basic
  • Last Updated : 06 Aug, 2021

The numpy.isinf() function tests element-wise whether it is +ve or -ve infinity or not return the result as a boolean array. 

Syntax: numpy.isinf(array [, out])

Parameters :  

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array : [array_like]Input array or object whose 
         elements, we need to test for  infinity
out   : [ndarray, optional]Output array placed 
        with result. Its type is preserved and
        it  must be of the right shape to hold 
         the output.

Return :  

boolean array containing the result. For scalar 
input, the result is a new boolean with value
True if the input is positive or negative infinity; 
otherwise the value is False. For array input, the 
result is a boolean array with the same shape as 
the input and the values are True where the 
corresponding element of the input is positive
or negative infinity; elsewhere the values are False.

Code 1 :  


# Python Program illustrating
# numpy.isinf() method
import numpy as geek
print("Finite : ", geek.isinf(1), "\n")
print("Finite : ", geek.isinf(0), "\n")
# not a number
print("Finite : ", geek.isinf(geek.nan), "\n")
#  infinity
print("Finite : ", geek.isinf(geek.inf), "\n")
print("Finite : ", geek.isinf(geek.NINF), "\n")
x = geek.array([-geek.inf, 0., geek.inf])
y = geek.array([2, 2, 2])
print("Checking for infinity : ", geek.isinf(x, y))

Output : 

Finite :  False 

Finite :  False 

Finite :  False 

Finite :  True 

Finite :  True 

Checking for infinity :  [1 0 1]

Code 2 : 


# Python Program illustrating
# numpy.isinf() method
import numpy as geek
# Returns True/False value for each element
b = geek.arange(8).reshape(2, 4)
print("\nIs Infinity : \n", geek.isinf(b))
# geek.inf  : Positive Infinity
# geek.NINF : negative Infinity
b = [[geek.inf],
print("\nIs Infinity : \n", geek.isinf(b))

Output : 

 [[0 1 2 3]
 [4 5 6 7]]

Is Infinity : 
 [[False False False False]
 [False False False False]]

Is Infinity : 
 [[ True]
 [ True]]

References :

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 or mail your article to See your article appearing on the GeeksforGeeks main page and help other Geeks.
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