Class NumpyIndexingAdapter

xarray/core/indexing.py:1682–1746

Wrap a NumPy array to use explicit indexing.

class NumpyIndexingAdapter(IndexingAdapter):
    """Wrap a NumPy array to use explicit indexing."""

    __slots__ = ("array",)

    def __init__(self, array):
        # In NumpyIndexingAdapter we only allow to store bare np.ndarray
        if not isinstance(array, np.ndarray):
            raise TypeError(
                "NumpyIndexingAdapter only wraps np.ndarray. "
                f"Trying to wrap {type(array)}"
            )
        self.array = array

    def transpose(self, order):
        return self.array.transpose(order)

    def _oindex_get(self, indexer: OuterIndexer):
        key = _outer_to_numpy_indexer(indexer, self.array.shape)
        return self.array[key]

    def _vindex_get(self, indexer: VectorizedIndexer):
        _assert_not_chunked_indexer(indexer.tuple)
        array = NumpyVIndexAdapter(self.array)
        return array[indexer.tuple]

    def __getitem__(self, indexer: ExplicitIndexer):
        self._check_and_raise_if_non_basic_indexer(indexer)

        array = self.array
        # We want 0d slices rather than scalars. This is achieved by
        # appending an ellipsis (see
        # https://numpy.org/doc/stable/reference/arrays.indexing.html#detailed-notes).
        key = indexer.tuple + (Ellipsis,)
        return array[key]

    def _safe_setitem(self, array, key: tuple[Any, ...], value: Any) -> None:
        try:
            array[key] = value
        except ValueError as exc:
            # More informative exception if read-only view
            if not array.flags.writeable and not array.flags.owndata:
                raise ValueError(
                    "Assignment destination is a view.  "
                    "Do you want to .copy() array first?"
                ) from exc
            else:
                raise exc

    def _oindex_set(self, indexer: OuterIndexer, value: Any) -> None:
        key = _outer_to_numpy_indexer(indexer, self.array.shape)
        self._safe_setitem(self.array, key, value)

    def _vindex_set(self, indexer: VectorizedIndexer, value: Any) -> None:
        array = NumpyVIndexAdapter(self.array)
        self._safe_setitem(array, indexer.tuple, value)

    def __setitem__(self, indexer: ExplicitIndexer, value: Any) -> None: