def _get_coarse_dataset(self, key, info):
        """Get the coarse dataset refered to by `key` from the XML data."""
        angles = self.root.find('.//Tile_Angles')
        if key in ['solar_zenith_angle', 'solar_azimuth_angle']:
            elts = angles.findall(info['xml_tag'] + '/Values_List/VALUES')
            return np.array([[val for val in elt.text.split()] for elt in elts],
                            dtype=np.float)

        elif key in ['satellite_zenith_angle', 'satellite_azimuth_angle']:
            arrays = []
            elts = angles.findall(info['xml_tag'] + '[@bandId="1"]')
            for elt in elts:
                items = elt.findall(info['xml_item'] + '/Values_List/VALUES')
                arrays.append(np.array([[val for val in item.text.split()] for item in items],
                                       dtype=np.float))
            return np.nanmean(np.dstack(arrays), -1)
        else:
            return
Get the coarse dataset refered to by `key` from the XML data.