Add getPrimalDualIntegral() from C API (#1174)

* Expose SCIPgetPrimalDualIntegral
* Add test
* Update CHANGELOG.md

Author: justinokamoto

CHANGELOG.md

@@ -8,6 +8,7 @@
 - Added pre-commit hook for automatic stub regeneration (see .pre-commit-config.yaml)
 - Wrapped isObjIntegral() and test
 - Added structured_optimization_trace recipe for structured optimization progress tracking
+- Added methods: getPrimalDualIntegral()
 ### Fixed
 - getBestSol() now returns None for infeasible problems instead of a Solution with NULL pointer
 - all fundamental callbacks now raise an error if not implemented

src/pyscipopt/scip.pxd

@@ -1473,6 +1473,7 @@ cdef extern from "scip/scip.h":
     int SCIPgetPlungeDepth(SCIP* scip)
     SCIP_Longint SCIPgetNNodeLPIterations(SCIP* scip)
     SCIP_Longint SCIPgetNStrongbranchLPIterations(SCIP* scip)
+    SCIP_Real SCIPgetPrimalDualIntegral(SCIP* scip)
 
     # Parameter Functions
     SCIP_RETCODE SCIPsetBoolParam(SCIP* scip, char* name, SCIP_Bool value)

src/pyscipopt/scip.pxi

@@ -3385,6 +3385,16 @@ cdef class Model:
         """
         return SCIPgetNStrongbranchLPIterations(self._scip)
 
+    def getPrimalDualIntegral(self):
+        """
+        Recomputes and returns the primal dual gap stored in the stats
+
+        Returns
+        ------
+        float
+        """
+        return SCIPgetPrimalDualIntegral(self._scip)
+
     def cutoffNode(self, Node node):
         """
         marks node and whole subtree to be cut off from the branch and bound tree.

src/pyscipopt/scip.pyi

@@ -1129,6 +1129,7 @@ class Model:
     def getNSols(self) -> Incomplete: ...
     def getNSolsFound(self) -> Incomplete: ...
     def getNStrongbranchLPIterations(self) -> Incomplete: ...
+    def getPrimalDualIntegral(self) -> Incomplete: ...
     def getNTotalNodes(self) -> Incomplete: ...
     def getNVars(self, transformed: Incomplete = ...) -> Incomplete: ...
     def getNVarsAnd(self, and_cons: Incomplete) -> Incomplete: ...

tests/test_statistics.py

@@ -12,3 +12,10 @@ def test_statistics_json():
         assert data["origprob"]["problem_name"] == "model"
 
     os.remove("statistics.json")
+
+def test_getPrimalDualIntegral():
+    model = random_mip_1(small=True)
+    model.optimize()
+    primal_dual_integral = model.getPrimalDualIntegral()
+
+    assert isinstance(primal_dual_integral, float)