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

Another method if you're stuck on <2.6, you don't have numpy, and you don't have IEEE 754 support:

def isNaN(x):
    return str(x) == str(1e400*0)