Warnings in DirectionalVariogram

[mmaelicke]

Hey @redhog
I get some warnings in the new code in DirectionalVariogram

scikit-gstat/skgstat/DirectionalVariogram.py:343: RuntimeWarning: invalid value encountered in true_divide
  pos_angles = np.arccos(scalar / self._euclidean_dist)
scikit-gstat/skgstat/DirectionalVariogram.py:637: RuntimeWarning: invalid value encountered in greater
  absdiff = np.where(absdiff > np.pi, absdiff - np.pi, absdiff)
scikit-gstat/skgstat/DirectionalVariogram.py:638: RuntimeWarning: invalid value encountered in greater
  absdiff = np.where(absdiff > np.pi / 2, np.pi - absdiff, absdiff)
scikit-gstat/skgstat/DirectionalVariogram.py:640: RuntimeWarning: invalid value encountered in less_equal
  in_tol = absdiff <= np.radians(self.tolerance / 2)
scikit-gstat/skgstat/DirectionalVariogram.py:641: RuntimeWarning: invalid value encountered in greater_equal
  in_band = self.bandwidth / 2 >= np.abs(dists * np.sin(np.abs(angles + np.radians(self.azimuth))))

There seems to be a problem with either some undefined state, which we forgot to set in preprocessing, or a missing call to preprocessing.
The second option are np.NaN values somewhere in one of the strings.

The Warnings do not pop up if you run the init a second time.

Do you have any clue right now, where this could be caused?

Edit: From what I can tell, the instance is nevertheless working as expected...