changing y axis label for heating plots (#2859)

Co-authored-by: Paul Romano <paul.k.romano@gmail.com>

openmc/plotter.py

@@ -73,24 +73,37 @@ def _get_legend_label(this, type):
 def _get_yaxis_label(reactions, divisor_types):
     """Gets a y axis label for the type of data plotted"""
 
-    if all(isinstance(item, str) for item in reactions.keys()):
-        stem = 'Microscopic'
-        if divisor_types:
-            mid, units = 'Data', ''
-        else:
-            mid, units = 'Cross Section', '[b]'
+    heat_values = {"heating", "heating-local", "damage-energy"}
+
+    # if all the types are heating a different stem and unit is needed
+    if all(set(value).issubset(heat_values) for value in reactions.values()):
+        stem = "Heating"
+    elif all(isinstance(item, str) for item in reactions.keys()):
+        for nuc_reactions in reactions.values():
+            for reaction in nuc_reactions:
+                if reaction in heat_values:
+                    raise TypeError(
+                        "Mixture of heating and Microscopic reactions. "
+                        "Invalid type for plotting"
+                    )
+        stem = "Microscopic"
     elif all(isinstance(item, openmc.Material) for item in reactions.keys()):
         stem = 'Macroscopic'
-        if divisor_types:
-            mid, units = 'Data', ''
-        else:
-            mid, units = 'Cross Section', '[1/cm]'
     else:
         msg = "Mixture of openmc.Material and elements/nuclides. Invalid type for plotting"
         raise TypeError(msg)
 
-    return f'{stem} {mid} {units}'
+    if divisor_types:
+        mid, units = "Data", ""
+    else:
+        mid = "Cross Section"
+        units = {
+            "Macroscopic": "[1/cm]",
+            "Microscopic": "[b]",
+            "Heating": "[eV-barn]",
+        }[stem]
 
+    return f'{stem} {mid} {units}'
 
 def _get_title(reactions):
     """Gets a title for the type of data plotted"""

tests/unit_tests/test_plotter.py

@@ -118,6 +118,21 @@ def test_plot_axes_labels():
     )
     assert axis_label == 'Microscopic Cross Section [b]'
 
+    axis_label = openmc.plotter._get_yaxis_label(
+        reactions={
+            "Li": ["heating", "heating-local"],
+            "Li7": ["heating"],
+            "Be": ["damage-energy"],
+        },
+        divisor_types=False,
+    )
+    assert axis_label == "Heating Cross Section [eV-barn]"
+
+    with pytest.raises(TypeError):
+        axis_label = openmc.plotter.plot_xs(
+            reactions={"Li": ["heating", "heating-local"], "Be9": ["(n,2n)"]}
+        )
+
     # just materials
     mat1 = openmc.Material()
     mat1.add_nuclide('Fe56', 1)