Class Index

xarray/core/indexes.py:39–488

Base class inherited by all xarray-compatible indexes. Do not use this class directly for creating index objects. Xarray indexes are created exclusively from subclasses of ``Index``, mostly via Xarray's public API like ``Dataset.set_xindex``. Every subclass must at least imple

class Index:
    """
    Base class inherited by all xarray-compatible indexes.

    Do not use this class directly for creating index objects. Xarray indexes
    are created exclusively from subclasses of ``Index``, mostly via Xarray's
    public API like ``Dataset.set_xindex``.

    Every subclass must at least implement :py:meth:`Index.from_variables`. The
    (re)implementation of the other methods of this base class is optional but
    mostly required in order to support operations relying on indexes such as
    label-based selection or alignment.

    The ``Index`` API closely follows the :py:meth:`Dataset` and
    :py:meth:`DataArray` API, e.g., for an index to support ``.sel()`` it needs
    to implement :py:meth:`Index.sel`, to support ``.stack()`` and
    ``.unstack()`` it needs to implement :py:meth:`Index.stack` and
    :py:meth:`Index.unstack`, etc.

    When a method is not (re)implemented, depending on the case the
    corresponding operation on a :py:meth:`Dataset` or :py:meth:`DataArray`
    either will raise a ``NotImplementedError`` or will simply drop/pass/copy
    the index from/to the result.

    Do not use this class directly for creating index objects.
    """

    @classmethod
    def from_variables(
        cls,
        variables: Mapping[Any, Variable],
        *,
        options: Mapping[str, Any],
    ) -> Self:
        """Create a new index object from one or more coordinate variables.

        This factory method must be implemented in all subclasses of Index.

        The coordinate variables may be passed here in an arbitrary number and
        order and each with arbitrary dimensions. It is the responsibility of
        the index to check the consistency and validity of these coordinates.

        Parameters
        ----------
        variables : dict-like
            Mapping of :py:class:`Variable` objects holding the coordinate labels
            to index.
        options : dict-like
            Keyword arguments passed to this constructor. Propagated from
            the ``**options`` argument of :py:meth:`xarray.DataArray.set_xindex`
            or :py:meth:`xarray.Dataset.set_xindex`.

        Returns
        -------
        index : Index
            A new Index object.
        """
        raise NotImplementedError()