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

In Python 3.6 checking on a string value x math.isnan(x) and np.isnan(x) raises an error. So I can't check if the given value is NaN or not if I don't know beforehand it's a number. The following seems to solve this issue

if str(x)=='nan' and type(x)!='str':
    print ('NaN')
else:
    print ('non NaN')