Revert "Fix is_total_slice for size-1 dimensions (#1800)"

docs/release.rst

@@ -25,6 +25,9 @@ Unreleased
 
 Enhancements
 ~~~~~~~~~~~~
+* Revert "Performance improvement for reading and writing chunks if any of the dimensions is size 1."
+  By :user:`Deepak Cherian <dcherian>`. :issue:`1874`.
+
 
 Docs
 ~~~~

zarr/tests/test_core.py

@@ -3157,3 +3157,47 @@ def test_issue_1279(tmpdir):
 
     written_data = ds_reopened[:]
     assert_array_equal(data, written_data)
+
+
+def test_scalar_indexing():
+    # regression test for #1874
+    store = zarr.KVStore({})
+
+    store["a"] = zarr.create((3,), chunks=(1,), store=store)
+    store["a"][:] = [1, 2, 3]
+
+    assert store["a"][1] == np.array(2.0)
+    assert store["a"][(1,)] == np.array(2.0)
+
+    store["a"][0] = [-1]
+    assert store["a"][0] == np.array(-1)
+
+    store["a"][0] = -2
+    assert store["a"][0] == np.array(-2)
+
+    store["a"][0] = (-3,)
+    assert store["a"][0] == np.array(-3)
+
+
+def test_object_array_indexing():
+    # regression test for #1874
+    from numcodecs import MsgPack
+
+    root = zarr.group()
+    arr = root.create_dataset(
+        name="my_dataset",
+        shape=0,
+        dtype=object,
+        object_codec=MsgPack(),
+    )
+    new_items = [
+        ["A", 1],
+        ["B", 2, "hello"],
+    ]
+    arr_add = np.empty(len(new_items), dtype=object)
+    arr_add[:] = new_items
+    arr.append(arr_add)
+
+    elem = ["C", 3]
+    arr[0] = elem
+    assert arr[0] == elem

zarr/tests/test_util.py

@@ -89,15 +89,6 @@ def test_is_total_slice():
     assert not is_total_slice((slice(0, 50), slice(0, 50)), (100, 100))
     assert not is_total_slice((slice(0, 100, 2), slice(0, 100)), (100, 100))
 
-    # size-1 dimension edge-case
-    # https://github.com/zarr-developers/zarr-python/issues/1730
-    assert is_total_slice((slice(0, 1),), (1,))
-    # this is an equivalent selection (without a slice)
-    assert is_total_slice((0,), (1,))
-    # same for multidimensional selection
-    assert is_total_slice((slice(0, 1), slice(0, 10)), (1, 10))
-    assert is_total_slice((0, slice(0, 10)), (1, 10))
-
     with pytest.raises(TypeError):
         is_total_slice("foo", (100,))
 

zarr/util.py

@@ -234,17 +234,8 @@ def is_total_slice(item, shape: Tuple[int]) -> bool:
     if isinstance(item, tuple):
         return all(
             (
-                (
-                    isinstance(it, slice)
-                    and (
-                        (it == slice(None))
-                        or ((it.stop - it.start == sh) and (it.step in [1, None]))
-                    )
-                )
-                # The only scalar edge case, indexing with int 0 along a size-1 dimension
-                # is identical to a total slice
-                # https://github.com/zarr-developers/zarr-python/issues/1730
-                or (isinstance(it, int) and it == 0 and sh == 1)
+                isinstance(it, slice)
+                and ((it == slice(None)) or ((it.stop - it.start == sh) and (it.step in [1, None])))
             )
             for it, sh in zip(item, shape)
         )