Merge e354202 into 788b6f9

docs/src/whatsnew/latest.rst

@@ -80,6 +80,9 @@ This document explains the changes made to Iris for this release
 #. `@bouweandela`_ made :meth:`iris.cube.Cube.rolling_window` work with lazy
    data. (:pull:`5795`)
 
+#. `@bouweandela`_ updated :meth:`iris.cube.CubeList.concatenate` so it keeps
+   ancillary variables and cell measures lazy. (:pull:`6010`)
+
 🔥 Deprecations
 ===============
 

lib/iris/_concatenate.py

@@ -1145,7 +1145,7 @@ def _build_cell_measures(self):
                 # Concatenate the data together.
                 dim = dims.index(self.axis)
                 data = [
-                    skton.signature.cell_measures_and_dims[i].coord.data
+                    skton.signature.cell_measures_and_dims[i].coord.core_data()
                     for skton in skeletons
                 ]
                 data = concatenate_arrays(tuple(data), axis=dim)
@@ -1185,7 +1185,7 @@ def _build_ancillary_variables(self):
                 # Concatenate the data together.
                 dim = dims.index(self.axis)
                 data = [
-                    skton.signature.ancillary_variables_and_dims[i].coord.data
+                    skton.signature.ancillary_variables_and_dims[i].coord.core_data()
                     for skton in skeletons
                 ]
                 data = concatenate_arrays(tuple(data), axis=dim)

lib/iris/tests/integration/concatenate/test_concatenate.py

@@ -12,6 +12,7 @@
 import iris.tests as tests  # isort:skip
 
 import cf_units
+import dask.array as da
 import numpy as np
 
 from iris._concatenate import _DerivedCoordAndDims, concatenate
@@ -157,6 +158,16 @@ def test_ignore_diff_cell_measure(self):
         self.assertEqual(len(result), 1)
         self.assertEqual(result[0].shape, (4, 2))
 
+    def test_lazy_cell_measure(self):
+        cube_a = self.create_cube()
+        cube_a.cell_measure("volume").data = da.array([0, 15])
+        cube_b = cube_a.copy()
+        cube_b.coord("time").points = [12, 18]
+
+        result = concatenate([cube_a, cube_b])
+        assert len(result) == 1
+        assert result[0].cell_measure("volume").has_lazy_data()
+
 
 class Test_cubes_with_ancillary_variables(tests.IrisTest):
     def create_cube(self):
@@ -194,6 +205,16 @@ def test_ignore_diff_ancillary_variables(self):
         self.assertEqual(len(result), 1)
         self.assertEqual(result[0].shape, (4, 2))
 
+    def test_lazy_ancillary_variables(self):
+        cube_a = self.create_cube()
+        cube_a.ancillary_variable("quality").data = da.array([0, 15])
+        cube_b = cube_a.copy()
+        cube_b.coord("time").points = [12, 18]
+
+        result = concatenate([cube_a, cube_b])
+        assert len(result) == 1
+        assert result[0].ancillary_variable("quality").has_lazy_data()
+
 
 class Test_cubes_with_derived_coord(tests.IrisTest):
     def create_cube(self):