Ensure contiguous data using astype (zarr-developers#513)

Previously we were calling `ascontiguousarray` and `asfortranarray`
based on whether we wanted a C or Fortran ordered array. However we can
simplify this by using `astype` to capture both cases. Additionally
those functions ensure the array is at least 1-D, but that doesn't seem
to matter for this use case since the scalar case is handled in a
different branch. So we leave that part out.

docs/release.rst

@@ -43,6 +43,9 @@ Upcoming Release
 * Use ``ensure_ndarray`` in a few more places.
   By :user:`John Kirkham <jakirkham>`; :issue:`506`.
 
+* Ensure contiguous data using ``astype``.
+  By :user:`John Kirkham <jakirkham>`; :issue:`513`.
+
 * Refactor out ``_tofile``/``_fromfile`` from ``DirectoryStore``.
   By :user:`John Kirkham <jakirkham>`; :issue:`503`.
 

zarr/core.py

@@ -1684,10 +1684,7 @@ def _chunk_setitem_nosync(self, chunk_coords, chunk_selection, value, fields=Non
             else:
 
                 # ensure array is contiguous
-                if self._order == 'F':
-                    chunk = np.asfortranarray(value, dtype=self._dtype)
-                else:
-                    chunk = np.ascontiguousarray(value, dtype=self._dtype)
+                chunk = value.astype(self._dtype, order=self._order, copy=False)
 
         else:
             # partially replace the contents of this chunk