pyfabm/c: implement missing_value for conserved quantities

src/c/fabm_c.F90

@@ -476,7 +476,7 @@ function get_variable(pmodel, category, index) bind(c) result(pvariable)
       case (HORIZONTAL_DIAGNOSTIC_VARIABLE)
          variable => model%p%horizontal_diagnostic_variables(index)%original
       case (CONSERVED_QUANTITY)
-         variable => model%p%conserved_quantities(index)%target
+         variable => model%p%conserved_quantities(index)%target_hz
       case (INTERIOR_DEPENDENCY, HORIZONTAL_DEPENDENCY, SCALAR_DEPENDENCY)
          select case (category)
          case (INTERIOR_DEPENDENCY);   domain = domain_interior

src/pyfabm/__init__.py

@@ -592,7 +592,7 @@ def __getitem__(self, key: str) -> Union[float, int, bool]:
         raise KeyError
 
 
-class Variable(object):
+class Variable:
     def __init__(
         self,
         model: "Model",
@@ -855,6 +855,19 @@ def reset(self):
         self.model._update_configuration(settings)
 
 
+class ConservedQuantity(Variable):
+    def __init__(
+        self, model: "Model", name: str, units: str, variable_pointer: ctypes.c_void_p
+    ):
+        super().__init__(model, name, units, name.replace("_", " "))
+        self._pvariable = variable_pointer
+
+    @property
+    def missing_value(self) -> float:
+        """Value that indicates missing data, for instance, on land."""
+        return self.model.fabm.variable_get_missing_value(self._pvariable)
+
+
 class StandardVariable:
     def __init__(self, model: "Model", pointer: ctypes.c_void_p):
         self.model = model
@@ -1055,7 +1068,7 @@ def __init__(
         self.bottom_state_variables: NamedObjectList[StateVariable] = NamedObjectList()
         self.interior_diagnostic_variables: NamedObjectList[DiagnosticVariable] = NamedObjectList()
         self.horizontal_diagnostic_variables: NamedObjectList[DiagnosticVariable] = NamedObjectList()
-        self.conserved_quantities: NamedObjectList[Variable] = NamedObjectList()
+        self.conserved_quantities: NamedObjectList[ConservedQuantity] = NamedObjectList()
         self.parameters: NamedObjectList[Parameter] = NamedObjectList()
         self.interior_dependencies: NamedObjectList[Dependency] = NamedObjectList()
         self.horizontal_dependencies: NamedObjectList[Dependency] = NamedObjectList()
@@ -1364,13 +1377,13 @@ def _update_configuration(self, settings: Optional[Tuple] = None):
                 strlong_name,
                 strpath,
             )
+            ptr = self.fabm.get_variable(self.pmodel, CONSERVED_QUANTITY, i + 1)
             self.conserved_quantities._data.append(
-                Variable(
+                ConservedQuantity(
                     self,
                     strname.value.decode("ascii"),
                     strunits.value.decode("ascii"),
-                    strlong_name.value.decode("ascii"),
-                    strpath.value.decode("ascii"),
+                    ptr,
                 )
             )
         for i in range(nparameters.value):
@@ -1427,7 +1440,9 @@ def _update_configuration(self, settings: Optional[Tuple] = None):
 
         self.itime = -1.0
 
-    def getRates(self, t: Optional[float] = None, surface: bool = True, bottom: bool = True):
+    def getRates(
+        self, t: Optional[float] = None, surface: bool = True, bottom: bool = True
+    ):
         """Returns the local rate of change in state variables,
         given the current state and environment.
         """
@@ -1501,6 +1516,9 @@ def get_vertical_movement(self, out: Optional[np.ndarray] = None) -> np.ndarray:
         return out
 
     def get_conserved_quantities(self, out: Optional[np.ndarray] = None) -> np.ndarray:
+        """Return depth-integrated values across the horizontal domain for all
+        conserved quantities
+        """
         assert (
             self._cell_thickness is not None
         ), "You must assign model.cell_thickness to use get_conserved_quantities"