fix: sharding codec with fancy indexing

changes/2817.bugfix.rst

@@ -0,0 +1 @@
+Fix fancy indexing (e.g. arr[5, [0, 1]]) with the sharding codec

src/zarr/codecs/sharding.py

@@ -529,7 +529,11 @@ async def _decode_partial_single(
             ],
             out,
         )
-        return out
+
+        if hasattr(indexer, "sel_shape"):
+            return out.reshape(indexer.sel_shape)
+        else:
+            return out
 
     async def _encode_single(
         self,

src/zarr/core/indexing.py

@@ -34,7 +34,7 @@
     from zarr.core.common import ChunkCoords
 
 IntSequence = list[int] | npt.NDArray[np.intp]
-ArrayOfIntOrBool = npt.NDArray[np.intp] | npt.NDArray[np.bool_]
+ArrayOfIntOrBool = IntSequence | npt.NDArray[np.bool_]
 BasicSelector = int | slice | EllipsisType
 Selector = BasicSelector | ArrayOfIntOrBool
 BasicSelection = BasicSelector | tuple[BasicSelector, ...]  # also used for BlockIndex

tests/test_array.py

@@ -1420,3 +1420,18 @@ def test_multiprocessing(store: Store, method: Literal["fork", "spawn", "forkser
 
     results = pool.starmap(_index_array, [(arr, slice(len(data)))])
     assert all(np.array_equal(r, data) for r in results)
+
+
+async def test_sharding_coordinate_selection() -> None:
+    store = MemoryStore()
+    g = zarr.open_group(store, mode="w")
+    arr = g.create_array(
+        name="a",
+        shape=(2, 3, 4),
+        chunks=(1, 2, 2),
+        overwrite=True,
+        dtype=np.float32,
+        shards=(2, 4, 4),
+    )
+    arr[:] = np.arange(2 * 3 * 4).reshape((2, 3, 4))
+    assert (arr[1, [0, 1]] == np.array([[12, 13, 14, 15], [16, 17, 18, 19]])).all()