add subcatchment surface buildup API functionality

- added buildup property to Subcatchment class
- added subcatch_buildup method for obtaining subcatchment surface buildup values

pyswmm/subcatchments.py

@@ -579,3 +579,14 @@ def statistics(self):
         :rtype: dict
         """
         return self._model.subcatch_statistics(self.subcatchmentid)
+
+    @property
+    def buildup(self):
+        """
+        Subcatchment surface buildup.
+        Number of values present depends on number of pollutants present.
+        
+        :return: Group of subcatchment surface buildup values/counts.
+        :rtype: dict
+        """
+        return self._model.subcatch_buildup(self.subcatchmentid)

pyswmm/swmm5.py

@@ -1352,6 +1352,55 @@ def subcatch_statistics(self, ID):
                     object_stats, attr)
         return out_dict
 
+    def subcatch_buildup(self, ID):
+        """
+        Get surface buildup for a Subcatchment.
+
+        :param str ID: Subcatchment ID
+        :return: Subcatchment surface buildup.
+        :rtype: dict
+        """
+        index = self.getObjectIDIndex(tka.ObjectType.SUBCATCH.value, ID)
+
+        # SWMM function handle.
+        swmm_subcbuildup_func = self.SWMMlibobj.swmm_getSubcatchBuildup
+        # SWMM function handle argument output structure.
+        swmm_subcbuildup_func_arg = ctypes.POINTER(tka.SubcBuildup)
+        # Define argument.
+        swmm_subcbuildup_func.argtypes = (
+            ctypes.c_int,
+            swmm_subcbuildup_func_arg, )
+
+        object_buildup = tka.SubcBuildup()
+        errcode = swmm_subcbuildup_func(
+            ctypes.c_int(index), ctypes.byref(object_buildup))
+
+        self._error_check(errcode)
+        # Copy Items to Dictionary using Alias Names.
+        out_dict = {}
+        for attr in dir(object_buildup): 
+            if "_" not in attr:
+                # Pollutant Array.
+                if attr == "subcatchBuildup":
+                    out_dict[object_buildup._py_alias_ids[attr]] = {}
+                    buildup_array = getattr(object_buildup, attr)
+                    pollut_ids = self.getObjectIDList(
+                        tka.ObjectType.POLLUT.value)                    
+                    if len(pollut_ids) > 0:
+                        for ind in range(len(pollut_ids)):
+                            out_dict[object_buildup._py_alias_ids[attr]][
+                                pollut_ids[ind]] = buildup_array[ind]
+                else:
+                    out_dict[object_buildup._py_alias_ids[attr]] = getattr(
+                        object_buildup, attr)
+
+        # Free Subcatchment Buildup Pollutant Array.
+        freesubcatchbuildup = self.SWMMlibobj.swmm_freeSubcatchBuildup
+        freesubcatchbuildup.argtypes = (swmm_subcbuildup_func_arg, )
+        freesubcatchbuildup(object_buildup)
+
+        return out_dict
+
     def flow_routing_stats(self):
         """
         Get Flow Routing System stats.

pyswmm/toolkitapi.py

@@ -282,6 +282,13 @@ class SubcStats(ctypes.Structure):
         "maxFlow": "peak_runoff_rate"
     }
 
+
+class SubcBuildup(ctypes.Structure):
+    _fields_ = [("subcatchBuildup", PollutArray)]
+    _py_alias_ids = {
+        "subcatchBuildup": "subcatchment_surface_buildup"
+    }
+
 
 class RoutingTotals(ctypes.Structure):
     _fields_ = [("dwInflow", ctypes.c_double), ("wwInflow", ctypes.c_double),