code: def load_map_coordinates(map_file):
      
      if map_file[-4:] == ".pkl":
          map_data = pickle.load(open(map_file))
          lon = map_data['lon']
          lat = map_data['lat']
      else:
          map_data = Dataset(map_file)
          if "lon" in map_data.variables.keys():
              lon = map_data.variables['lon'][:]
              lat = map_data.variables['lat'][:]
          else:
              lon = map_data.variables["XLONG"][0]
              lat = map_data.variables["XLAT"][0]
      return lon, lat
docs: Loads map coordinates from netCDF or pickle file created by util.makeMapGrids.
  
      Args:
          map_file: Filename for the file containing coordinate information.
  
      Returns:
          Latitude and longitude grids as numpy arrays.