Fix copy to include Ancillary variables and Cell measures

docs/iris/src/whatsnew/contributions_3.0.0/bugfix_2019-Nov-19_cell_measure_copy_loss.txt

@@ -0,0 +1,2 @@
+* Copying a cube would previously ignore any attached class:`iris.coords.CellMeasure`.
+  These are now copied over.

lib/iris/analysis/__init__.py

@@ -186,7 +186,7 @@ def matches_any(self, predicate):
         return any(self.matches(predicate))
 
 
-def coord_comparison(*cubes):
+def coord_comparison(*cubes, object_get=None):
     """
     Convenience function to help compare coordinates on one or more cubes
     by their metadata.
@@ -240,7 +240,12 @@ def coord_comparison(*cubes):
         print('All equal coordinates: ', result['equal'])
 
     """
-    all_coords = [cube.coords() for cube in cubes]
+    if object_get is None:
+        from iris.cube import Cube
+
+        object_get = Cube.coords
+
+    all_coords = [object_get(cube) for cube in cubes]
     grouped_coords = []
 
     # set of coordinates id()s of coordinates which have been processed
@@ -334,15 +339,15 @@ def diff_shape_fn(cube, coord):
         # dimension on their respective cubes
         # (None -> group describes a different dimension)
         def diff_data_dim_fn(cube, coord):
-            return cube.coord_dims(coord) != first_cube.coord_dims(first_coord)
+            return coord.cube_dims(cube) != first_coord.cube_dims(first_cube)
 
         if coord_group.matches_any(diff_data_dim_fn):
             different_data_dimension.add(coord_group)
 
         # get all coordinate groups which don't describe a dimension
         # (None -> doesn't describe a dimension)
         def no_data_dim_fn(cube, coord):
-            return cube.coord_dims(coord) == ()
+            return coord.cube_dims(cube) == ()
 
         if coord_group.matches_all(no_data_dim_fn):
             no_data_dimension.add(coord_group)

lib/iris/cube.py

@@ -3522,6 +3522,12 @@ def _deepcopy(self, memo, data=None):
 
         new_dim_coords_and_dims = deepcopy(self._dim_coords_and_dims, memo)
         new_aux_coords_and_dims = deepcopy(self._aux_coords_and_dims, memo)
+        new_cell_measures_and_dims = deepcopy(
+            self._cell_measures_and_dims, memo
+        )
+        new_ancillary_variables_and_dims = deepcopy(
+            self._ancillary_variables_and_dims, memo
+        )
 
         # Record a mapping from old coordinate IDs to new coordinates,
         # for subsequent use in creating updated aux_factories.
@@ -3541,6 +3547,8 @@ def _deepcopy(self, memo, data=None):
             dm.core_data(),
             dim_coords_and_dims=new_dim_coords_and_dims,
             aux_coords_and_dims=new_aux_coords_and_dims,
+            cell_measures_and_dims=new_cell_measures_and_dims,
+            ancillary_variables_and_dims=new_ancillary_variables_and_dims,
         )
 
         new_cube.metadata = deepcopy(self.metadata, memo)
@@ -3567,13 +3575,23 @@ def __eq__(self, other):
                 )
 
             if result:
-                result = set(self._cell_measures_and_dims) == set(
-                    other._cell_measures_and_dims
+                coord_comparison = iris.analysis.coord_comparison(
+                    self, other, object_get=Cube.cell_measures,
+                )
+                # if there are any cell measures which are not equal
+                result = not (
+                    coord_comparison["not_equal"]
+                    or coord_comparison["non_equal_data_dimension"]
                 )
 
             if result:
-                result = set(self._ancillary_variables_and_dims) == set(
-                    other._ancillary_variables_and_dims
+                coord_comparison = iris.analysis.coord_comparison(
+                    self, other, object_get=Cube.ancillary_variables,
+                )
+                # if there are any ancillary variables which are not equal
+                result = not (
+                    coord_comparison["not_equal"]
+                    or coord_comparison["non_equal_data_dimension"]
                 )
 
             # Having checked everything else, check approximate data equality.

lib/iris/tests/unit/cube/test_Cube.py

@@ -1710,6 +1710,18 @@ def test(self):
         cube = stock.simple_3d()
         self._check_copy(cube, cube.copy())
 
+    def test_copy_ancillary_variables(self):
+        cube = stock.simple_3d()
+        avr = AncillaryVariable([2, 3], long_name="foo")
+        cube.add_ancillary_variable(avr, 0)
+        self._check_copy(cube, cube.copy())
+
+    def test_copy_cell_measures(self):
+        cube = stock.simple_3d()
+        cms = CellMeasure([2, 3], long_name="foo")
+        cube.add_cell_measure(cms, 0)
+        self._check_copy(cube, cube.copy())
+
     def test__masked_emptymask(self):
         cube = Cube(ma.array([0, 1]))
         self._check_copy(cube, cube.copy())
@@ -2268,15 +2280,15 @@ def test_ancillary_diff_data(self):
     def test_cell_measure_fail(self):
         cube1 = Cube([0, 1])
         cube2 = Cube([0, 1])
-        cms = CellMeasure([2, 3], measure="area", long_name="foo")
+        cms = CellMeasure([2, 3], long_name="foo")
         cube2.add_cell_measure(cms, 0)
         self.assertFalse(cube1 == cube2)
 
     def test_cell_measure_reorder(self):
         cube1 = Cube([0, 1])
         cube2 = Cube([0, 1])
-        cms1 = CellMeasure([2, 3], measure="area", long_name="foo")
-        cms2 = CellMeasure([4, 5], measure="area", long_name="bar")
+        cms1 = CellMeasure([2, 3], long_name="foo")
+        cms2 = CellMeasure([4, 5], long_name="bar")
         # Add the same cell measure to cube1 and cube2 in
         # opposite orders.
         cube1.add_cell_measure(cms1, 0)
@@ -2288,8 +2300,8 @@ def test_cell_measure_reorder(self):
     def test_cell_measure_diff_data(self):
         cube1 = Cube([0, 1])
         cube2 = Cube([0, 1])
-        cms1 = CellMeasure([2, 3], measure="area", long_name="foo")
-        cms2 = CellMeasure([4, 5], measure="area", long_name="foo")
+        cms1 = CellMeasure([2, 3], long_name="foo")
+        cms2 = CellMeasure([4, 5], long_name="foo")
         cube1.add_cell_measure(cms1, 0)
         cube2.add_cell_measure(cms2, 0)
         self.assertFalse(cube1 == cube2)