def _set_subset_indices(self, y_min, y_max, x_min, x_max):
        """
        load subset based on extent
        """
        y_coords, x_coords = self.xd.lsm.coords
        dx = self.xd.lsm.dx
        dy = self.xd.lsm.dy

        lsm_y_indices_from_y, lsm_x_indices_from_y = \
            np.where((y_coords >= (y_min - 2*dy)) &
                     (y_coords <= (y_max + 2*dy)))
        lsm_y_indices_from_x, lsm_x_indices_from_x = \
            np.where((x_coords >= (x_min - 2*dx)) &
                     (x_coords <= (x_max + 2*dx)))

        lsm_y_indices = np.intersect1d(lsm_y_indices_from_y,
                                       lsm_y_indices_from_x)
        lsm_x_indices = np.intersect1d(lsm_x_indices_from_y,
                                       lsm_x_indices_from_x)

        self.xslice = slice(np.amin(lsm_x_indices),
                            np.amax(lsm_x_indices)+1)
        self.yslice = slice(np.amin(lsm_y_indices),
                            np.amax(lsm_y_indices)+1)
load subset based on extent