# numpy.isnan () in Python

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numpy.isnan (array [, out]): Tests element by element if it is NaN or not, returns the result as a boolean array ...
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 program illustrating ` ` # numpy.isnan () method `   ` import ` ` numpy as geek ` ` `  ` print ` ` (` ` "Is NaN:" ` ` , geek.isnan (` ` 1 ` `), ` ` "" ` `) `   ` print ` ` (` ` "Is NaN:" ` `, geek.isnan (` ` 0 ` `), ` ` "" ` `) `   ` # not a number ` ` print ` ` (` ` "Is NaN:" ` `, geek.isnan (geek.nan), ` ` "" ` `) `   ` # infinity ` ` print ` ` (` `" Is NaN: "` `, geek.isnan ( geek.inf), ` ` "" ` `) `   ` print ` ` (` `" Is NaN : "` `, geek.isnan (geek.NINF), ` `" "` ` ) `   ` 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 program illustrating ` ` # numpy.isnan ( ) method `   ` import ` ` numpy as geek `   ` # Returns True / False for each element ` ` b ` ` = ` ` geek.arange (` ` 20 ` `). reshape (` ` 5 ` `, ` ` 4 ` `) `   ` print ` ` (` `" "` `, b) ` ` print ` ` (` ` "Is NaN (Not a Number ): "` `, geek.isnan (b)) ` ` `    ` b ` ` = ` ` [[` ` 1j ` `], ` ` [geek.nan]] ` ` print ` ` (` ` "Is NaN (Not a Number):" ` `, geek.isnan (b)) `

Outut:

` [[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]] `

Notes:
These codes will not work for online IDs. Please run them on your systems to see how they work.
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