def lat_id(self, line):
        ''' Return the corresponding latitude

        Args:
            line (int): Line number

        Returns:
            Correponding latitude in degree
        '''
        if self.grid == 'WAC':
            lat = ((1 + self.LINE_PROJECTION_OFFSET - line) *
                   self.MAP_SCALE * 1e-3 / self.A_AXIS_RADIUS)
            return lat * 180 / np.pi
        else:
            lat = float(self.CENTER_LATITUDE) - \
                (line - float(self.LINE_PROJECTION_OFFSET) - 1)\
                / float(self.MAP_RESOLUTION)
            return lat