Method unstack

xarray/core/dataset.py:5544–5645

Unstack existing dimensions corresponding to MultiIndexes into multiple new dimensions. New dimensions will be added at the end. Parameters ---------- dim : str, Iterable of Hashable or None, optional Dimension(s) over which to unstack.

(
        self,
        dim: Dims = None,
        *,
        fill_value: Any = xrdtypes.NA,
        sparse: bool = False,
    )

        )

    def unstack(
        self,
        dim: Dims = None,
        *,
        fill_value: Any = xrdtypes.NA,
        sparse: bool = False,
    ) -> Self:
        """
        Unstack existing dimensions corresponding to MultiIndexes into
        multiple new dimensions.

        New dimensions will be added at the end.

        Parameters
        ----------
        dim : str, Iterable of Hashable or None, optional
            Dimension(s) over which to unstack. By default unstacks all
            MultiIndexes.
        fill_value : scalar or dict-like, default: nan
            value to be filled. If a dict-like, maps variable names to
            fill values. If not provided or if the dict-like does not
            contain all variables, the dtype's NA value will be used.
        sparse : bool, default: False
            use sparse-array if True

        Returns
        -------
        unstacked : Dataset
            Dataset with unstacked data.

        See Also
        --------
        Dataset.stack
        """

        if dim is None:
            dims = list(self.dims)
        else:
            if isinstance(dim, str) or not isinstance(dim, Iterable):
                dims = [dim]
            else:
                dims = list(dim)

            missing_dims = set(dims) - set(self.dims)
            if missing_dims:
                raise ValueError(
                    f"Dimensions {tuple(missing_dims)} not found in data dimensions {tuple(self.dims)}"
                )

        # each specified dimension must have exactly one multi-index
        stacked_indexes: dict[Any, tuple[Index, dict[Hashable, Variable]]] = {}
        for d in dims:
            idx, idx_vars = self._get_stack_index(d, multi=True)
            if idx is not None:
                stacked_indexes[d] = idx, idx_vars

        if dim is None:
            dims = list(stacked_indexes)