Splitattrs ncload

docs/src/further_topics/metadata.rst

@@ -131,7 +131,7 @@ We can easily get all of the associated metadata of the :class:`~iris.cube.Cube`
 using the ``metadata`` property:
 
     >>> cube.metadata
-    CubeMetadata(standard_name='air_temperature', long_name=None, var_name='air_temperature', units=Unit('K'), attributes=CubeAttrsDict(globals={}, locals={'Conventions': 'CF-1.5', 'STASH': STASH(model=1, section=3, item=236), 'Model scenario': 'A1B', 'source': 'Data from Met Office Unified Model 6.05'}), cell_methods=(CellMethod(method='mean', coord_names=('time',), intervals=('6 hour',), comments=()),))
+    CubeMetadata(standard_name='air_temperature', long_name=None, var_name='air_temperature', units=Unit('K'), attributes=CubeAttrsDict(globals={'Conventions': 'CF-1.5'}, locals={'STASH': STASH(model=1, section=3, item=236), 'Model scenario': 'A1B', 'source': 'Data from Met Office Unified Model 6.05'}), cell_methods=(CellMethod(method='mean', coord_names=('time',), intervals=('6 hour',), comments=()),))
 
 We can also inspect the ``metadata`` of the ``longitude``
 :class:`~iris.coords.DimCoord` attached to the :class:`~iris.cube.Cube` in the same way:
@@ -676,7 +676,7 @@ For example, consider the following :class:`~iris.common.metadata.CubeMetadata`,
 .. doctest:: metadata-combine
 
     >>> cube.metadata
-    CubeMetadata(standard_name='air_temperature', long_name=None, var_name='air_temperature', units=Unit('K'), attributes=CubeAttrsDict(globals={}, locals={'Conventions': 'CF-1.5', 'STASH': STASH(model=1, section=3, item=236), 'Model scenario': 'A1B', 'source': 'Data from Met Office Unified Model 6.05'}), cell_methods=(CellMethod(method='mean', coord_names=('time',), intervals=('6 hour',), comments=()),))
+    CubeMetadata(standard_name='air_temperature', long_name=None, var_name='air_temperature', units=Unit('K'), attributes=CubeAttrsDict(globals={'Conventions': 'CF-1.5'}, locals={'STASH': STASH(model=1, section=3, item=236), 'Model scenario': 'A1B', 'source': 'Data from Met Office Unified Model 6.05'}), cell_methods=(CellMethod(method='mean', coord_names=('time',), intervals=('6 hour',), comments=()),))
 
 We can perform the **identity function** by comparing the metadata with itself,
 
@@ -811,7 +811,7 @@ the ``from_metadata`` class method. For example, given the following
 .. doctest:: metadata-convert
 
     >>> cube.metadata
-    CubeMetadata(standard_name='air_temperature', long_name=None, var_name='air_temperature', units=Unit('K'), attributes=CubeAttrsDict(globals={}, locals={'Conventions': 'CF-1.5', 'STASH': STASH(model=1, section=3, item=236), 'Model scenario': 'A1B', 'source': 'Data from Met Office Unified Model 6.05'}), cell_methods=(CellMethod(method='mean', coord_names=('time',), intervals=('6 hour',), comments=()),))
+    CubeMetadata(standard_name='air_temperature', long_name=None, var_name='air_temperature', units=Unit('K'), attributes=CubeAttrsDict(globals={'Conventions': 'CF-1.5'}, locals={'STASH': STASH(model=1, section=3, item=236), 'Model scenario': 'A1B', 'source': 'Data from Met Office Unified Model 6.05'}), cell_methods=(CellMethod(method='mean', coord_names=('time',), intervals=('6 hour',), comments=()),))
 
 We can easily convert it to a :class:`~iris.common.metadata.DimCoordMetadata` instance
 using ``from_metadata``,

lib/iris/fileformats/_nc_load_rules/helpers.py

@@ -433,9 +433,9 @@ def build_cube_metadata(engine):
     # Set the cube global attributes.
     for attr_name, attr_value in cf_var.cf_group.global_attributes.items():
         try:
-            cube.attributes[str(attr_name)] = attr_value
+            cube.attributes.globals[str(attr_name)] = attr_value
         except ValueError as e:
-            msg = "Skipping global attribute {!r}: {}"
+            msg = "Skipping disallowed global attribute {!r}: {}"
             warnings.warn(msg.format(attr_name, str(e)))
 
 

lib/iris/fileformats/netcdf/loader.py

@@ -159,8 +159,13 @@ def attribute_predicate(item):
         return item[0] not in _CF_ATTRS
 
     tmpvar = filter(attribute_predicate, cf_var.cf_attrs_unused())
+    attrs_dict = iris_object.attributes
+    if hasattr(attrs_dict, "locals"):
+        # Treat cube attributes (i.e. a CubeAttrsDict) as a special case.
+        # These attrs are "local" (i.e. on the variable), so record them as such.
+        attrs_dict = attrs_dict.locals
     for attr_name, attr_value in tmpvar:
-        _set_attributes(iris_object.attributes, attr_name, attr_value)
+        _set_attributes(attrs_dict, attr_name, attr_value)
 
 
 def _get_actual_dtype(cf_var):

lib/iris/tests/integration/test_netcdf__loadsaveattrs.py

@@ -25,7 +25,7 @@
 
 import iris
 import iris.coord_systems
-from iris.cube import Cube
+from iris.cube import Cube, CubeAttrsDict
 import iris.fileformats.netcdf
 import iris.fileformats.netcdf._thread_safe_nc as threadsafe_nc4
 
@@ -633,8 +633,13 @@ def test_01_userstyle_single_global(self):
         )
         # Default behaviour for a general global user-attribute.
         # It is attached to all loaded cubes.
-        assert cube1.attributes == {"myname": "single-value"}
-        assert cube2.attributes == {"myname": "single-value"}
+
+        expected_dict = {"myname": "single-value"}
+        for cube in (cube1, cube2):
+            # #1 : legacy results, for cube.attributes **viewed as a plain dictionary**.
+            assert dict(cube1.attributes) == expected_dict
+            # #2 : exact expected result, viewed as newstyle split-attributes
+            assert cube1.attributes == CubeAttrsDict(globals=expected_dict)
 
     def test_02_userstyle_single_local(self):
         # Default behaviour for a general local user-attribute.
@@ -658,10 +663,26 @@ def test_03_userstyle_multiple_different(self):
             global_value_file2="global_file2",
             vars_values_file2=vars2,
         )
-        assert cube1.attributes == {"random": "f1v1"}
-        assert cube2.attributes == {"random": "f1v2"}
-        assert cube3.attributes == {"random": "x1"}
-        assert cube4.attributes == {"random": "x2"}
+
+        # (#1) : legacy equivalence : for cube.attributes viewed as a plain 'dict'
+        assert dict(cube1.attributes) == {"random": "f1v1"}
+        assert dict(cube2.attributes) == {"random": "f1v2"}
+        assert dict(cube3.attributes) == {"random": "x1"}
+        assert dict(cube4.attributes) == {"random": "x2"}
+
+        # (#1) : exact results check, for newstyle "split" cube attrs
+        assert cube1.attributes == CubeAttrsDict(
+            globals={"random": "global_file1"}, locals={"random": "f1v1"}
+        )
+        assert cube2.attributes == CubeAttrsDict(
+            globals={"random": "global_file1"}, locals={"random": "f1v2"}
+        )
+        assert cube3.attributes == CubeAttrsDict(
+            globals={"random": "global_file2"}, locals={"random": "x1"}
+        )
+        assert cube4.attributes == CubeAttrsDict(
+            globals={"random": "global_file2"}, locals={"random": "x2"}
+        )
 
     def test_04_userstyle_multiple_same(self):
         # Nothing special to note in this case
@@ -671,8 +692,14 @@ def test_04_userstyle_multiple_same(self):
             global_value_file1="global_file1",
             vars_values_file1={"v1": "same-value", "v2": "same-value"},
         )
-        assert cube1.attributes == {"random": "same-value"}
-        assert cube2.attributes == {"random": "same-value"}
+        for cube in (cube1, cube2):
+            # (#1): legacy values, for cube.attributes viewed as a single dict
+            assert dict(cube.attributes) == {"random": "same-value"}
+            # (#2): exact results, with newstyle "split" cube attrs
+            assert cube2.attributes == CubeAttrsDict(
+                globals={"random": "global_file1"},
+                locals={"random": "same-value"},
+            )
 
     #######################################################
     # Tests on "Conventions" attribute.
@@ -702,7 +729,13 @@ def test_08_conventions_var_both(self):
             global_value_file1="global-setting",
             vars_values_file1="local-setting",
         )
-        assert cube.attributes == {"Conventions": "local-setting"}
+        # (#1): legacy values, for cube.attributes viewed as a single dict
+        assert dict(cube.attributes) == {"Conventions": "local-setting"}
+        # (#2): exact results, with newstyle "split" cube attrs
+        assert cube.attributes == CubeAttrsDict(
+            globals={"Conventions": "global-setting"},
+            locals={"Conventions": "local-setting"},
+        )
 
     #######################################################
     # Tests on "global" style attributes
@@ -725,7 +758,12 @@ def test_10_globalstyle__local(self, global_attr):
             attr_name=global_attr,
             vars_values_file1=attr_content,
         )
-        assert cube.attributes == {global_attr: attr_content}
+        # (#1): legacy values, for cube.attributes viewed as a single dict
+        assert dict(cube.attributes) == {global_attr: attr_content}
+        # (#2): exact results, with newstyle "split" cube attrs
+        assert cube.attributes == CubeAttrsDict(
+            locals={global_attr: attr_content}
+        )
 
     def test_11_globalstyle__both(self, global_attr):
         attr_global = f"Global-{global_attr}"
@@ -736,7 +774,13 @@ def test_11_globalstyle__both(self, global_attr):
             vars_values_file1=attr_local,
         )
         # promoted local setting "wins"
-        assert cube.attributes == {global_attr: attr_local}
+        # (#1): legacy values, for cube.attributes viewed as a single dict
+        assert dict(cube.attributes) == {global_attr: attr_local}
+        # (#2): exact results, with newstyle "split" cube attrs
+        assert cube.attributes == CubeAttrsDict(
+            globals={global_attr: attr_global},
+            locals={global_attr: attr_local},
+        )
 
     def test_12_globalstyle__multivar_different(self, global_attr):
         # Multiple *different* local settings are retained
@@ -746,8 +790,12 @@ def test_12_globalstyle__multivar_different(self, global_attr):
             attr_name=global_attr,
             vars_values_file1={"v1": attr_1, "v2": attr_2},
         )
-        assert cube1.attributes == {global_attr: attr_1}
-        assert cube2.attributes == {global_attr: attr_2}
+        # (#1): legacy values, for cube.attributes viewed as a single dict
+        assert dict(cube1.attributes) == {global_attr: attr_1}
+        assert dict(cube2.attributes) == {global_attr: attr_2}
+        # (#2): exact results, with newstyle "split" cube attrs
+        assert cube1.attributes == CubeAttrsDict(locals={global_attr: attr_1})
+        assert cube2.attributes == CubeAttrsDict(locals={global_attr: attr_2})
 
     def test_14_globalstyle__multifile_different(self, global_attr):
         # Different global attributes from multiple files are retained as local ones
@@ -812,7 +860,15 @@ def test_16_localstyle(self, local_attr, origin_style):
                 # For some reason, these ones never appear on the cube
                 expected_result = {}
 
-        assert cube.attributes == expected_result
+        if origin_style == "input_local":
+            expected_result_newstyle = CubeAttrsDict(expected_result)
+        else:
+            expected_result_newstyle = CubeAttrsDict(globals=expected_result)
+
+        # (#1): legacy values, for cube.attributes viewed as a single dict
+        assert dict(cube.attributes) == expected_result
+        # (#2): exact results, with newstyle "split" cube attrs
+        assert cube.attributes == expected_result_newstyle
 
 
 class TestSave(MixinAttrsTesting):

lib/iris/tests/unit/fileformats/nc_load_rules/helpers/test_build_cube_metadata.py

@@ -42,7 +42,7 @@ def _make_engine(global_attributes=None, standard_name=None, long_name=None):
     return engine
 
 
-class TestInvalidGlobalAttributes(tests.IrisTest):
+class TestGlobalAttributes(tests.IrisTest):
     def test_valid(self):
         global_attributes = {
             "Conventions": "CF-1.5",
@@ -51,7 +51,7 @@ def test_valid(self):
         engine = _make_engine(global_attributes)
         build_cube_metadata(engine)
         expected = global_attributes
-        self.assertEqual(engine.cube.attributes, expected)
+        self.assertEqual(engine.cube.attributes.globals, expected)
 
     def test_invalid(self):
         global_attributes = {
@@ -65,13 +65,14 @@ def test_invalid(self):
         # Check for a warning.
         self.assertEqual(warn.call_count, 1)
         self.assertIn(
-            "Skipping global attribute 'calendar'", warn.call_args[0][0]
+            "Skipping disallowed global attribute 'calendar'",
+            warn.call_args[0][0],
         )
         # Check resulting attributes. The invalid entry 'calendar'
         # should be filtered out.
         global_attributes.pop("calendar")
         expected = global_attributes
-        self.assertEqual(engine.cube.attributes, expected)
+        self.assertEqual(engine.cube.attributes.globals, expected)
 
 
 class TestCubeName(tests.IrisTest):