Class _DummyGroup

xarray/core/groupby.py:186–251

Class for keeping track of grouped dimensions without coordinates. Should not be user visible.

class _DummyGroup(Generic[T_Xarray]):
    """Class for keeping track of grouped dimensions without coordinates.

    Should not be user visible.
    """

    __slots__ = ("coords", "dataarray", "name", "size")

    def __init__(self, obj: T_Xarray, name: Hashable, coords) -> None:
        self.name = name
        self.coords = coords
        self.size = obj.sizes[name]

    @property
    def dims(self) -> tuple[Hashable]:
        return (self.name,)

    @property
    def ndim(self) -> Literal[1]:
        return 1

    @property
    def values(self) -> range:
        return range(self.size)

    @property
    def data(self) -> np.ndarray:
        return np.arange(self.size, dtype=int)

    def __array__(
        self, dtype: np.typing.DTypeLike | None = None, /, *, copy: bool | None = None
    ) -> np.ndarray:
        if copy is False:
            raise NotImplementedError(f"An array copy is necessary, got {copy = }.")
        return np.arange(self.size)

    @property
    def shape(self) -> tuple[int, ...]:
        return (self.size,)

    @property
    def attrs(self) -> dict:
        return {}

    def __getitem__(self, key):
        if isinstance(key, tuple):
            (key,) = key
        return self.values[key]

    def to_index(self) -> pd.Index:
        # could be pd.RangeIndex?
        return pd.Index(np.arange(self.size))

    def copy(self, deep: bool = True, data: Any = None):
        raise NotImplementedError

    def to_dataarray(self) -> DataArray:
        from xarray.core.dataarray import DataArray