Add async oindex method to AsyncArray

src/zarr/core/array.py

@@ -79,6 +79,7 @@
     MaskIndexer,
     MaskSelection,
     OIndex,
+    AsyncOIndex,
     OrthogonalIndexer,
     OrthogonalSelection,
     Selection,
@@ -1358,6 +1359,21 @@
         )
         return await self._get_selection(indexer, prototype=prototype)
 
+    async def get_orthogonal_selection(
+        self,
+        selection: OrthogonalSelection,
+        *,
+        out: NDBuffer | None = None,
+        fields: Fields | None = None,
+        prototype: BufferPrototype | None = None,
+    ) -> NDArrayLike:
+        if prototype is None:
+            prototype = default_buffer_prototype()
+        indexer = OrthogonalIndexer(selection, self.shape, self.metadata.chunk_grid)
+        return await self._get_selection(
+            indexer=indexer, out=out, fields=fields, prototype=prototype
+        )
+
     async def _save_metadata(self, metadata: ArrayMetadata, ensure_parents: bool = False) -> None:
         """
         Asynchronously save the array metadata.
@@ -1488,6 +1504,12 @@
         )
         return await self._set_selection(indexer, value, prototype=prototype)
 
+    @property
+    def oindex(self) -> AsyncOIndex:
+        """Shortcut for orthogonal (outer) indexing, see :func:`get_orthogonal_selection` and
+        :func:`set_orthogonal_selection` for documentation and examples."""
+        return AsyncOIndex(self)
+
     async def resize(self, new_shape: ShapeLike, delete_outside_chunks: bool = True) -> None:
         """
         Asynchronously resize the array to a new shape.

src/zarr/core/indexing.py

@@ -28,7 +28,7 @@
 from zarr.core.common import product
 
 if TYPE_CHECKING:
-    from zarr.core.array import Array
+    from zarr.core.array import Array, AsyncArray
     from zarr.core.buffer import NDArrayLikeOrScalar
     from zarr.core.chunk_grids import ChunkGrid
     from zarr.core.common import ChunkCoords
@@ -950,7 +950,7 @@
         return self.array.get_orthogonal_selection(
             cast(OrthogonalSelection, new_selection), fields=fields
         )
-
+    
     def __setitem__(self, selection: OrthogonalSelection, value: npt.ArrayLike) -> None:
         fields, new_selection = pop_fields(selection)
         new_selection = ensure_tuple(new_selection)
@@ -960,6 +960,25 @@
         )
 
 
+@dataclass(frozen=True)
+class AsyncOIndex:
+    array: AsyncArray
+
+    async def getitem(self, selection: OrthogonalSelection | Array) -> NDArrayLike:
+        from zarr.core.array import Array
+
+        # if input is a Zarr array, we materialize it now.
+        if isinstance(selection, Array):
+            selection = _zarr_array_to_int_or_bool_array(selection)
+
+        fields, new_selection = pop_fields(selection)
+        new_selection = ensure_tuple(new_selection)
+        new_selection = replace_lists(new_selection)
+        return await self.array.get_orthogonal_selection(
+            cast(OrthogonalSelection, new_selection), fields=fields
+        )
+
+
 @dataclass(frozen=True)
 class BlockIndexer(Indexer):
     dim_indexers: list[SliceDimIndexer]