Method set_xindex

xarray/core/dataset.py:5002–5116

Set a new, Xarray-compatible index from one or more existing coordinate(s). Existing index(es) on the coord(s) will be replaced. Parameters ---------- coord_names : str or list Name(s) of the coordinate(s) used to build the index. If several n

(
        self,
        coord_names: str | Sequence[Hashable],
        index_cls: type[Index] | None = None,
        **options,
    )

        )

    def set_xindex(
        self,
        coord_names: str | Sequence[Hashable],
        index_cls: type[Index] | None = None,
        **options,
    ) -> Self:
        """Set a new, Xarray-compatible index from one or more existing
        coordinate(s). Existing index(es) on the coord(s) will be replaced.

        Parameters
        ----------
        coord_names : str or list
            Name(s) of the coordinate(s) used to build the index.
            If several names are given, their order matters.
        index_cls : subclass of :class:`~xarray.indexes.Index`, optional
            The type of index to create. By default, try setting
            a ``PandasIndex`` if ``len(coord_names) == 1``,
            otherwise a ``PandasMultiIndex``.
        **options
            Options passed to the index constructor.

        Returns
        -------
        obj : Dataset
            Another dataset, with this dataset's data and with a new index.

        """
        # the Sequence check is required for mypy
        if is_scalar(coord_names) or not isinstance(coord_names, Sequence):
            coord_names = [coord_names]

        if index_cls is None:
            if len(coord_names) == 1:
                index_cls = PandasIndex
            else:
                index_cls = PandasMultiIndex
        elif not issubclass(index_cls, Index):
            raise TypeError(f"{index_cls} is not a subclass of xarray.Index")

        invalid_coords = set(coord_names) - self._coord_names

        if invalid_coords:
            msg = ["invalid coordinate(s)"]
            no_vars = invalid_coords - set(self._variables)
            data_vars = invalid_coords - no_vars
            if no_vars:
                msg.append(f"those variables don't exist: {no_vars}")
            if data_vars:
                msg.append(
                    f"those variables are data variables: {data_vars}, use `set_coords` first"
                )
            raise ValueError("\n".join(msg))

        coord_vars = {name: self._variables[name] for name in coord_names}

        index = index_cls.from_variables(coord_vars, options=options)

        new_coord_vars = index.create_variables(coord_vars)