```python
>>> import numpy as np
>>> a = np.array([1,2,np.NaN])
>>> b = np.array([1,2,np.NaN])
>>> c = np.array([2,3,4])
>>> np.any( a!= b )
True
>>> np.any( a != c )
True
```

`np.any` would return false positives, I think.

PS : Sorry, I logged in from another PC and forgot to Sign In through my acount.