Fix cell data parsing (#3848)

Author: GuySten

openmc/cell.py

@@ -747,15 +747,6 @@ def from_xml_element(cls, elem, surfaces, materials, get_universe):
             c.region = Region.from_expression(region, surfaces)
 
         # Check for other attributes
-        temperature = get_elem_list(elem, 'temperature', float)
-        if temperature is not None:
-            if len(temperature) > 1:
-                c.temperature = temperature
-            else:
-                c.temperature = temperature[0]
-        density = get_elem_list(elem, 'density', float)
-        if density is not None:
-            c.density = density if len(density) > 1 else density[0]
         v = get_text(elem, 'volume')
         if v is not None:
             c.volume = float(v)
@@ -764,6 +755,8 @@ def from_xml_element(cls, elem, surfaces, materials, get_universe):
             if values is not None:
                 if key == 'rotation' and len(values) == 9:
                     values = np.array(values).reshape(3, 3)
+                elif len(values) == 1:
+                    values = values[0]
                 setattr(c, key, values)
 
         # Add this cell to appropriate universe

tests/unit_tests/test_model.py

@@ -265,8 +265,8 @@ def test_import_properties(run_in_tmpdir, mpi_intracomm):
     # Check to see that values are assigned to the C and python representations
     # First python
     cell = model.geometry.get_all_cells()[1]
-    assert cell.temperature == [600.0]
-    assert cell.density == [pytest.approx(10.0, 1e-5)]
+    assert cell.temperature == 600.0
+    assert cell.density == pytest.approx(10.0, 1e-5)
     assert cell.fill.get_mass_density() == pytest.approx(5.0)
     # Now C
     assert openmc.lib.cells[1].get_temperature() == 600.
@@ -286,8 +286,8 @@ def test_import_properties(run_in_tmpdir, mpi_intracomm):
         'with_properties/settings.xml'
     )
     cell = model_with_properties.geometry.get_all_cells()[1]
-    assert cell.temperature == [600.0]
-    assert cell.density == [pytest.approx(10.0, 1e-5)]
+    assert cell.temperature == 600.0
+    assert cell.density == pytest.approx(10.0, 1e-5)
     assert cell.fill.get_mass_density() == pytest.approx(5.0)