arrays proxy

src/zarr/core/group.py

@@ -294,6 +294,36 @@ def flatten(
         return metadata
 
 
+class ArraysProxy:
+    """
+    Proxy for arrays in a group.
+
+    Used to implement the `Group.arrays` property
+    """
+
+    def __init__(self, group: Group) -> None:
+        self._group = group
+
+    def __getitem__(self, key: str) -> Array:
+        obj = self._group[key]
+        if isinstance(obj, Array):
+            return obj
+        raise KeyError(key)
+
+    def __setitem__(self, key: str, value: npt.ArrayLike) -> None:
+        """
+        Set an array in the group.
+        """
+        self._group._sync(self._group._async_group.set_array(key, value))
+
+    def __iter__(self) -> Generator[tuple[str, Array], None]:
+        for name, async_array in self._group._sync_iter(self._group._async_group.arrays()):
+            yield name, Array(async_array)
+
+    def __call__(self) -> Generator[tuple[str, Array], None]:
+        return iter(self)
+
+
 @dataclass(frozen=True)
 class GroupMetadata(Metadata):
     attributes: dict[str, Any] = field(default_factory=dict)
@@ -596,7 +626,16 @@ def from_dict(
             store_path=store_path,
         )
 
-    async def setitem(self, key: str, value: Any) -> None:
+    async def set_array(self, key: str, value: Any) -> None:
+        """fastpath for creating a new array
+
+        Parameters
+        ----------
+        key : str
+            Array name
+        value : array-like
+            Array data
+        """
         path = self.store_path / key
         await async_api.save_array(
             store=path, arr=value, zarr_format=self.metadata.zarr_format, exists_ok=True
@@ -1374,9 +1413,14 @@ def __iter__(self) -> Iterator[str]:
     def __len__(self) -> int:
         return self.nmembers()
 
+    @deprecated("Use Group.arrays setter instead.")
     def __setitem__(self, key: str, value: Any) -> None:
-        """Create a new array"""
-        self._sync(self._async_group.setitem(key, value))
+        """Create a new array
+
+        .. deprecated:: 3.0.0
+            Use Group.arrays.setter instead.
+        """
+        self._sync(self._async_group.set_array(key, value))
 
     def __repr__(self) -> str:
         return f"<Group {self.store_path}>"
@@ -1473,9 +1517,9 @@ def group_values(self) -> Generator[Group, None]:
         for _, group in self.groups():
             yield group
 
-    def arrays(self) -> Generator[tuple[str, Array], None]:
-        for name, async_array in self._sync_iter(self._async_group.arrays()):
-            yield name, Array(async_array)
+    @property
+    def arrays(self) -> ArraysProxy:
+        return ArraysProxy(self)
 
     def array_keys(self) -> Generator[str, None]:
         for name, _ in self.arrays():

tests/v3/test_group.py

@@ -392,7 +392,8 @@ def test_group_setitem(store: Store, zarr_format: ZarrFormat) -> None:
     """
     group = Group.from_store(store, zarr_format=zarr_format)
     arr = np.ones((2, 4))
-    group["key"] = arr
+    with pytest.warns(DeprecationWarning):
+        group["key"] = arr
     assert group["key"].shape == (2, 4)
     np.testing.assert_array_equal(group["key"][:], arr)
 
@@ -405,7 +406,8 @@ def test_group_setitem(store: Store, zarr_format: ZarrFormat) -> None:
 
     # overwrite with another array
     arr = np.zeros((3, 5))
-    group[key] = arr
+    with pytest.warns(DeprecationWarning):
+        group[key] = arr
     assert group[key].shape == (3, 5)
     np.testing.assert_array_equal(group[key], arr)
 
@@ -416,6 +418,31 @@ def test_group_setitem(store: Store, zarr_format: ZarrFormat) -> None:
     # assert group["key"][:] == 1
 
 
+def test_group_arrays_setter(store: Store, zarr_format: ZarrFormat) -> None:
+    """
+    Test the `Group.__setitem__` method.
+    """
+    group = Group.from_store(store, zarr_format=zarr_format)
+    arr = np.ones((2, 4))
+    group.arrays["key"] = arr
+    assert group["key"].shape == (2, 4)
+    np.testing.assert_array_equal(group["key"][:], arr)
+
+    if store.supports_deletes:
+        key = "key"
+    else:
+        # overwriting with another array requires deletes
+        # for stores that don't support this, we just use a new key
+        key = "key2"
+
+    # overwrite with another array
+    arr = np.zeros((3, 5))
+    with pytest.warns(DeprecationWarning):
+        group[key] = arr
+    assert group[key].shape == (3, 5)
+    np.testing.assert_array_equal(group[key], arr)
+
+
 def test_group_contains(store: Store, zarr_format: ZarrFormat) -> None:
     """
     Test the `Group.__contains__` method