remove UGRID constructs after collapse

Author: davidhassell

cf/field.py

@@ -6903,18 +6903,25 @@ def collapse(
 
             # ---------------------------------------------------------
             # Update dimension coordinates, auxiliary coordinates,
-            # cell measures and domain ancillaries
+            # cell measures, domain ancillaries, domain_topologies,
+            # and cell connectivities.
             # ---------------------------------------------------------
             for axis, domain_axis in collapse_axes.items():
                 # Ignore axes which are already size 1
                 size = domain_axis.get_size()
                 if size == 1:
                     continue
 
-                # REMOVE all cell measures and domain ancillaries
-                # which span this axis
+                # REMOVE all cell measures, domain ancillaries,
+                # domain_topologies, and cell connectivities which
+                # span this axis
                 c = f.constructs.filter(
-                    filter_by_type=("cell_measure", "domain_ancillary"),
+                    filter_by_type=(
+                        "cell_measure",
+                        "domain_ancillary",
+                        "domain_topology",
+                        "cell_connectivity",
+                    ),
                     filter_by_axis=(axis,),
                     axis_mode="or",
                     todict=True,

cf/test/test_collapse.py

@@ -1,6 +1,8 @@
+import atexit
 import datetime
 import faulthandler
 import os
+import tempfile
 import unittest
 
 import numpy
@@ -9,6 +11,25 @@
 
 import cf
 
+n_tmpfiles = 1
+tmpfiles = [
+    tempfile.mkstemp("_test_collapse.nc", dir=os.getcwd())[1]
+    for i in range(n_tmpfiles)
+]
+[tmpfile] = tmpfiles
+
+
+def _remove_tmpfiles():
+    """Try to remove defined temporary files by deleting their paths."""
+    for f in tmpfiles:
+        try:
+            os.remove(f)
+        except OSError:
+            pass
+
+
+atexit.register(_remove_tmpfiles)
+
 
 class Field_collapseTest(unittest.TestCase):
     def setUp(self):
@@ -791,6 +812,19 @@ def test_Field_collapse_non_positive_weights(self):
                     # compute time
                     g.array
 
+    def test_Field_collapse_ugrid(self):
+        """Check that UGRID constructs are removed after collapsing."""
+        f = cf.example_field(8)
+        self.assertTrue(f.domain_topologies())
+        self.assertTrue(f.cell_connectivities())
+
+        f = f.collapse("area: mean")
+        self.assertFalse(f.domain_topologies())
+        self.assertFalse(f.cell_connectivities())
+
+        # Check the collpsed fields writes
+        cf.write(f, tmpfile)
+
 
 if __name__ == "__main__":
     print("Run date:", datetime.datetime.now())