NaN in python and validity checking [duplicate]

Question

I'm doing a program where I optimize some values. Due to the equations, from time to time my values are NaN

My problem, some of the entries are NaN.

I would like to know if there is a test to check their logical validity so I can skip those values and retry.

So far I have tried checking for

a==np.nan, a==nan, b=a a==b

To no avail.

I hope you can help me

Thanks

Answer 1

Using numpy,

import numpy as np
np.isnan(np.nan) # returns True

Answer 2

Since Python 2.6, you want to import math and use math.isnan(a).

See http://docs.python.org/library/math.html#math.isnan