def _get_weights(self):
        """Returns weights used for collision matrix and |X> and |f>

        self._rot_grid_points : ndarray
            shape=(ir_grid_points, point_operations), dtype='uintp'

        r_gps : grid points of arms of k-star with duplicates
            len(r_gps) == order of crystallographic point group
            len(unique(r_gps)) == number of arms of the k-star

        Returns
        -------
        weights : list
            sqrt(g_k)/|g|, where g is the crystallographic point group and
            g_k is the number of arms of k-star.

        """
        weights = []
        n = float(self._rot_grid_points.shape[1])
        for r_gps in self._rot_grid_points:
            weights.append(np.sqrt(len(np.unique(r_gps)) / n))
        return weights
Returns weights used for collision matrix and |X> and |f>

        self._rot_grid_points : ndarray
            shape=(ir_grid_points, point_operations), dtype='uintp'

        r_gps : grid points of arms of k-star with duplicates
            len(r_gps) == order of crystallographic point group
            len(unique(r_gps)) == number of arms of the k-star

        Returns
        -------
        weights : list
            sqrt(g_k)/|g|, where g is the crystallographic point group and
            g_k is the number of arms of k-star.