Create a mask both for nan and inf values in an array

You can use np.isfinite(). It will return a boolean mask with True wherever the values are neither infinite nor NAN.

You can get the finite values this way:

a = np.asarray(a)
a = a[np.isfinite(a)]

Or for both arrays together:

mask = np.isfinite(a) | np.isfinite(b)
a = a[mask]
b = b[mask]

np.isfinite

Test element-wise for finiteness (not infinity or not Not a Number).