[v3] Makes data contiguous in v2 codec

src/zarr/codecs/_v2.py

@@ -5,6 +5,7 @@
 from typing import TYPE_CHECKING
 
 import numcodecs
+import numpy as np
 from numcodecs.compat import ensure_ndarray_like
 
 from zarr.abc.codec import ArrayBytesCodec
@@ -14,7 +15,15 @@
     import numcodecs.abc
 
     from zarr.core.array_spec import ArraySpec
-    from zarr.core.buffer import Buffer, NDBuffer
+    from zarr.core.buffer import Buffer, NDArrayLike, NDBuffer
+
+
+def ensure_contiguous(arr: NDArrayLike) -> NDArrayLike:
+    flags = getattr(arr, "flags", None)
+    if flags is not None and flags.c_contiguous:
+        return arr
+    else:
+        return np.ascontiguousarray(arr)
 
 
 @dataclass(frozen=True)
@@ -83,6 +92,7 @@ async def _encode_single(
         else:
             cdata = chunk
 
+        cdata = ensure_contiguous(ensure_ndarray_like(cdata))
         return chunk_spec.prototype.buffer.from_bytes(cdata)
 
     def compute_encoded_size(self, _input_byte_length: int, _chunk_spec: ArraySpec) -> int:

tests/test_v2.py

@@ -132,3 +132,27 @@ def test_v2_filters_codecs(filters: Any) -> None:
     arr[:] = array_fixture
     result = arr[:]
     np.testing.assert_array_equal(result, array_fixture)
+
+
+def test_v2_non_contiguous() -> None:
+    arr = zarr.Array.create(
+        MemoryStore({}),
+        shape=(10, 8),
+        chunks=(3, 3),
+        fill_value=np.nan,
+        dtype="float64",
+        zarr_format=2,
+        exists_ok=True,
+    )
+    a = np.ones(arr.shape)
+    arr[slice(6, 9, None), slice(3, 6, None)] = a[
+        slice(6, 9, None), slice(3, 6, None)
+    ]  # The slice on the RHS is important
+
+    a = np.ones((3, 3), order="F")
+    assert a.flags.f_contiguous
+    arr[slice(6, 9, None), slice(3, 6, None)] = a
+
+    a = np.ones((3, 3), order="C")
+    assert a.flags.c_contiguous
+    arr[slice(6, 9, None), slice(3, 6, None)] = a