def _update_mean_in_window(self):
        """
        Compute mean in window the slow way. useful for first step.

        Considers all values in window

        See Also
        --------
        _add_observation_to_means : fast update of mean for single observation addition
        _remove_observation_from_means : fast update of mean for single observation removal

        """
        self._mean_x_in_window = numpy.mean(self._x_in_window)
        self._mean_y_in_window = numpy.mean(self._y_in_window)
Compute mean in window the slow way. useful for first step.

        Considers all values in window

        See Also
        --------
        _add_observation_to_means : fast update of mean for single observation addition
        _remove_observation_from_means : fast update of mean for single observation removal