Merge pull request #58 from bcdev/forman-56-no_gobal_attrs

Attributes of target dataset no longer empty

CHANGES.md

@@ -2,6 +2,8 @@
 
 ### Fixes
 
+* Global metadata attributes of target dataset is no longer empty. [#56]
+
 * If the target _parent_ directory did not exist, an exception was raised 
   reporting that the lock file to be written does not exist. Changed this to
   report that the target parent directory does not exist. [#55]

tests/helpers.py

@@ -108,6 +108,10 @@ def make_test_dataset(
                 np.linspace(0, 1, shape[2], dtype="float64"), dims=dims[2]
             ),
         },
+        attrs={
+            "Conventions": "CF-1.8",
+            "title": f"Test {index + 1}-{index + shape[0]}",
+        },
     )
 
     if crs:

tests/test_api.py

@@ -26,14 +26,37 @@ def test_no_slices(self):
         zappend([], target_dir=target_dir)
         self.assertFalse(FileObj(target_dir).exists())
 
+    def test_one_slices_memory(self):
+        target_dir = "memory://target.zarr"
+        slices = [make_test_dataset()]
+        zappend(slices, target_dir=target_dir)
+        ds = xr.open_zarr(target_dir)
+        self.assertEqual({"time": 3, "y": 50, "x": 100}, ds.sizes)
+        self.assertEqual({"chl", "tsm"}, set(ds.data_vars))
+        self.assertEqual({"time", "y", "x"}, set(ds.coords))
+        self.assertEqual(
+            {
+                "Conventions": "CF-1.8",
+                "title": "Test 1-3",
+            },
+            ds.attrs,
+        )
+
     def test_some_slices_memory(self):
         target_dir = "memory://target.zarr"
-        slices = [make_test_dataset(), make_test_dataset(), make_test_dataset()]
+        slices = [make_test_dataset(index=3 * i) for i in range(3)]
         zappend(slices, target_dir=target_dir)
         ds = xr.open_zarr(target_dir)
         self.assertEqual({"time": 9, "y": 50, "x": 100}, ds.sizes)
         self.assertEqual({"chl", "tsm"}, set(ds.data_vars))
         self.assertEqual({"time", "y", "x"}, set(ds.coords))
+        self.assertEqual(
+            {
+                "Conventions": "CF-1.8",
+                "title": "Test 1-3",
+            },
+            ds.attrs,
+        )
 
     def test_some_slices_local(self):
         target_dir = "target.zarr"
@@ -42,14 +65,21 @@ def test_some_slices_local(self):
             "slice-2.zarr",
             "slice-3.zarr",
         ]
-        for uri in slices:
-            make_test_dataset(uri=uri)
+        for index, uri in enumerate(slices):
+            make_test_dataset(uri=uri, index=3 * index)
         try:
             zappend(slices, target_dir=target_dir)
             ds = xr.open_zarr(target_dir)
             self.assertEqual({"time": 9, "y": 50, "x": 100}, ds.sizes)
             self.assertEqual({"chl", "tsm"}, set(ds.data_vars))
             self.assertEqual({"time", "y", "x"}, set(ds.coords))
+            self.assertEqual(
+                {
+                    "Conventions": "CF-1.8",
+                    "title": "Test 1-3",
+                },
+                ds.attrs,
+            )
         finally:
             shutil.rmtree(target_dir, ignore_errors=True)
             for slice_dir in slices:
@@ -72,52 +102,74 @@ def test_some_slices_local_output_to_non_existing_dir(self):
 
     def test_some_slices_with_class_slice_source(self):
         target_dir = "memory://target.zarr"
-        slices = [make_test_dataset(), make_test_dataset(), make_test_dataset()]
+        slices = [make_test_dataset(index=3 * i) for i in range(3)]
         zappend(slices, target_dir=target_dir, slice_source=MySliceSource)
         ds = xr.open_zarr(target_dir)
         self.assertEqual({"time": 9, "y": 50, "x": 100}, ds.sizes)
         self.assertEqual({"chl"}, set(ds.data_vars))
         self.assertEqual({"time", "y", "x"}, set(ds.coords))
+        self.assertEqual(
+            {
+                "Conventions": "CF-1.8",
+                "title": "Test 1-3",
+            },
+            ds.attrs,
+        )
 
     def test_some_slices_with_func_slice_source(self):
         def process_slice(ctx, slice_ds: xr.Dataset) -> SliceSource:
             return MySliceSource(ctx, slice_ds)
 
         target_dir = "memory://target.zarr"
-        slices = [make_test_dataset(), make_test_dataset(), make_test_dataset()]
+        slices = [make_test_dataset(index=3 * i) for i in range(3)]
         zappend(slices, target_dir=target_dir, slice_source=process_slice)
         ds = xr.open_zarr(target_dir)
         self.assertEqual({"time": 9, "y": 50, "x": 100}, ds.sizes)
         self.assertEqual({"chl"}, set(ds.data_vars))
         self.assertEqual({"time", "y", "x"}, set(ds.coords))
+        self.assertEqual(
+            {
+                "Conventions": "CF-1.8",
+                "title": "Test 1-3",
+            },
+            ds.attrs,
+        )
 
     def test_some_slices_with_inc_append_step(self):
         target_dir = "memory://target.zarr"
-        slices = [
-            make_test_dataset(index=0, shape=(1, 50, 100)),
-            make_test_dataset(index=1, shape=(1, 50, 100)),
-            make_test_dataset(index=2, shape=(1, 50, 100)),
-        ]
+        slices = [make_test_dataset(index=i, shape=(1, 50, 100)) for i in range(3)]
         zappend(slices, target_dir=target_dir, append_step="1D")
         ds = xr.open_zarr(target_dir)
         np.testing.assert_array_equal(
             ds.time.values,
             np.array(["2024-01-01", "2024-01-02", "2024-01-03"], dtype=np.datetime64),
         )
+        self.assertEqual(
+            {
+                "Conventions": "CF-1.8",
+                "title": "Test 1-1",
+            },
+            ds.attrs,
+        )
 
     def test_some_slices_with_dec_append_step(self):
         target_dir = "memory://target.zarr"
         slices = [
-            make_test_dataset(index=2, shape=(1, 50, 100)),
-            make_test_dataset(index=1, shape=(1, 50, 100)),
-            make_test_dataset(index=0, shape=(1, 50, 100)),
+            make_test_dataset(index=i, shape=(1, 50, 100)) for i in reversed(range(3))
         ]
         zappend(slices, target_dir=target_dir, append_step="-1D")
         ds = xr.open_zarr(target_dir)
         np.testing.assert_array_equal(
             ds.time.values,
             np.array(["2024-01-03", "2024-01-02", "2024-01-01"], dtype=np.datetime64),
         )
+        self.assertEqual(
+            {
+                "Conventions": "CF-1.8",
+                "title": "Test 3-3",
+            },
+            ds.attrs,
+        )
 
     # # See https://github.com/bcdev/zappend/issues/21
     #

zappend/tailoring.py

@@ -40,9 +40,18 @@ def tailor_slice_dataset(
         # as dimension, e.g., "x", "y", "crs", ...
         dataset = dataset.drop_vars(const_variables)
 
+    # https://github.com/bcdev/zappend/issues/56
+    # slice_dataset.to_zarr(store, mode="a", ...) will replace
+    # global attributes.
+    # Therefore, we must replace slice dataset attributes by
+    # existing target dataset attributes.
+    # However, users should be able to select the appropriate
+    # operation, e.g., a new config setting target_attrs_op with
+    # values "first" (default), "last", "update".
+    dataset.attrs = target_metadata.attrs
+
     # Remove any encoding and attributes from slice,
     # since both are prescribed by target
-    dataset.attrs.clear()
     for variable in dataset.variables.values():
         variable.encoding = {}
         variable.attrs = {}