numpy.isnan() in Python

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 : 

Output : 

Is NaN : False 

Is NaN : False 

Is NaN : True 

Is NaN : False 

Is NaN : False 

Checking for NaN : [0 0 0]

Code 2 : 

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.