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# pandas.api.extensions.register_index_accessor

pandas.api.extensions.register_index_accessor(name)

  Register a custom accessor on Index objects.

  Parameters:
    namestr

      Name under which the accessor should be registered. A warning is issued if this name conflicts with a preexisting attribute.

  Returns:
    callable

      A class decorator.

  See also

  `register_dataframe_accessor`

    Register a custom accessor on DataFrame objects.

  `register_series_accessor`

    Register a custom accessor on Series objects.

  `register_index_accessor`

    Register a custom accessor on Index objects.

  Notes

  When accessed, your accessor will be initialized with the pandas object the user is interacting with. So the signature must be

      def __init__(self, pandas_object):  # noqa: E999
          ...

  For consistency with pandas methods, you should raise an `AttributeError` if the data passed to your accessor has an incorrect dtype.

      >>> pd.Series(['a', 'b']).dt
      Traceback (most recent call last):
      ...
      AttributeError: Can only use .dt accessor with datetimelike values

  Examples

  In your library code:

      import pandas as pd

      @pd.api.extensions.register_dataframe_accessor("geo")
      class GeoAccessor:
          def __init__(self, pandas_obj):
              self._obj = pandas_obj

          @property
          def center(self):
              # return the geographic center point of this DataFrame
              lat = self._obj.latitude
              lon = self._obj.longitude
              return (float(lon.mean()), float(lat.mean()))

          def plot(self):
              # plot this array's data on a map, e.g., using Cartopy
              pass

  Back in an interactive IPython session:

  >     In [1]: ds = pd.DataFrame({"longitude": np.linspace(0, 10),
  >        ...:                    "latitude": np.linspace(0, 20)})
  >     In [2]: ds.geo.center
  >     Out[2]: (5.0, 10.0)
  >     In [3]: ds.geo.plot()  # plots data on a map