Class PandasMultiIndex

xarray/core/indexes.py:1025–1483

Wrap a pandas.MultiIndex as an xarray compatible index.

class PandasMultiIndex(PandasIndex):
    """Wrap a pandas.MultiIndex as an xarray compatible index."""

    index: pd.MultiIndex
    dim: Hashable
    coord_dtype: Any
    level_coords_dtype: dict[Hashable | None, Any]

    __slots__ = ("coord_dtype", "dim", "index", "level_coords_dtype")

    def __init__(self, array: Any, dim: Hashable, level_coords_dtype: Any = None):
        super().__init__(array, dim)

        # default index level names
        names = []
        for i, idx in enumerate(self.index.levels):
            name = idx.name or f"{dim}_level_{i}"
            if name == dim:
                raise ValueError(
                    f"conflicting multi-index level name {name!r} with dimension {dim!r}"
                )
            names.append(name)
        self.index.names = names

        if level_coords_dtype is None:
            level_coords_dtype = {
                idx.name: get_valid_numpy_dtype(idx) for idx in self.index.levels
            }
        self.level_coords_dtype = level_coords_dtype

    def _replace(self, index, dim=None, level_coords_dtype=None) -> PandasMultiIndex:
        if dim is None:
            dim = self.dim
        index.name = dim
        if level_coords_dtype is None:
            level_coords_dtype = self.level_coords_dtype
        return type(self)(index, dim, level_coords_dtype)

    @classmethod
    def from_variables(
        cls,
        variables: Mapping[Any, Variable],
        *,
        options: Mapping[str, Any],
    ) -> PandasMultiIndex:
        _check_dim_compat(variables)
        dim = next(iter(variables.values())).dims[0]

        index = pd.MultiIndex.from_arrays(
            [var.values for var in variables.values()], names=list(variables.keys())
        )
        index.name = dim
        level_coords_dtype = {name: var.dtype for name, var in variables.items()}
        obj = cls(index, dim, level_coords_dtype=level_coords_dtype)

        return obj

    @classmethod