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

Last Updated : 08 Mar, 2024

The numpy.isnan() function tests element-wise whether it is NaN or not and returns the result as a boolean array. Syntax :

numpy.isnan(array [, out])

Parameters :

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 `

Python Program illustrating

numpy.isnan() method

import numpy as geek

print("Is NaN : ", geek.isnan(1), "\n")

print("Is NaN : ", geek.isnan(0), "\n")

not a number

print("Is NaN : ", geek.isnan(geek.nan), "\n")

infinity

print("Is NaN : ", geek.isnan(geek.inf), "\n")

print("Is NaN : ", geek.isnan(geek.NINF), "\n")

x = geek.array([-geek.inf, 0., geek.inf]) y = geek.array([2, 2, 2]) print("Checking for NaN : ", geek.isnan(x, y))

`

Output :

Is NaN : False

Is NaN : False

Is NaN : True

Is NaN : False

Is NaN : False

Checking for NaN : [0 0 0]

Code 2 :

Python `

Python Program illustrating

numpy.isnan() method

import numpy as geek

Returns True/False value for each element

b = geek.arange(20).reshape(5, 4)

print("\n",b) print("\nIs NaN(Not a Number): \n", geek.isnan(b))

b = [[1j], [geek.nan]] print("\nIs NaN(Not a Number) : \n", geek.isnan(b))

`

Output :

[[ 0 1 2 3] [ 4 5 6 7] [ 8 9 10 11] [12 13 14 15] [16 17 18 19]]

Is NaN(Not a Number): [[False False False False] [False False False False] [False False False False] [False False False False] [False False False False]]

Is NaN(Not a Number) : [[False] [ True]]

Note : These codes won't run on online IDE's. So please, run them on your systems to explore the working.