How can I check for NaN values?

Question

float(\'nan\') results in Nan (not a number). But how do I check for it? Should be very easy, but I cannot find it.

Answer 1

Well I entered this post, because i've had some issues with the function:

math.isnan()

There are problem when you run this code:

a = "hello"
math.isnan(a)

It raises exception. My solution for that is to make another check:

def is_nan(x):
    return isinstance(x, float) and math.isnan(x)