How to Check for NaN Values in Python

Using math.isnan Method

The math.isnan(x) method returns True if x is a NaN (not a number), and False otherwise. For example,

#!/usr/bin/python3

# Import module
import math

f = float('nan')
print(math.isnan(f))

True

Using NaN Implement

A NaN implemented following the standard, is the only value for which the inequality comparison with itself should return True:

#!/usr/bin/python3

def isNaN(n):
  return n != n

f = float('nan')
print(isNaN(f))

True