changes to improve custom Benders' plugin

src/pyscipopt/__init__.py

@@ -3,6 +3,7 @@
 # export user-relevant objects:
 from pyscipopt.Multidict import multidict
 from pyscipopt.scip      import Model
+from pyscipopt.scip      import Benders
 from pyscipopt.scip      import Branchrule
 from pyscipopt.scip      import Conshdlr
 from pyscipopt.scip      import Eventhdlr

src/pyscipopt/benders.pxi

@@ -28,16 +28,16 @@ cdef class Benders:
         return {}
 
     def benderspresubsolve(self, solution, enfotype, checkint):
-        pass
+        return {}
 
     def benderssolvesubconvex(self, solution, probnumber, onlyconvex):
-        pass
+        return {}
 
     def benderssolvesub(self, solution, probnumber):
-        pass
+        return {}
 
     def benderspostsolve(self, solution, enfotype, mergecandidates, npriomergecands, checkint, infeasible):
-        pass
+        return {}
 
     def bendersfreesub(self, probnumber):
         pass
@@ -46,6 +46,12 @@ cdef class Benders:
         print("python error in bendersgetvar: this method needs to be implemented")
         return {}
 
+# local helper functions for the interface
+cdef Variable getPyVar(SCIP_VAR* var):
+    cdef SCIP_VARDATA* vardata
+    vardata = SCIPvarGetData(var)
+    return <Variable>vardata
+
 
 cdef SCIP_RETCODE PyBendersCopy (SCIP* scip, SCIP_BENDERS* benders):
     return SCIP_OKAY
@@ -125,7 +131,7 @@ cdef SCIP_RETCODE PyBendersSolvesubconvex (SCIP* scip, SCIP_BENDERS* benders, SC
     PyBenders = <Benders>bendersdata
     solution = Solution()
     solution.sol = sol
-    result_dict = PyBenders.benderssolvesub(solution, probnumber, onlyconvex)
+    result_dict = PyBenders.benderssolvesubconvex(solution, probnumber, onlyconvex)
     objective[0] = result_dict.get("objective", 1e+20)
     result[0] = result_dict.get("result", <SCIP_RESULT>result[0])
     return SCIP_OKAY
@@ -169,12 +175,11 @@ cdef SCIP_RETCODE PyBendersGetvar (SCIP* scip, SCIP_BENDERS* benders, SCIP_VAR*
     cdef SCIP_BENDERSDATA* bendersdata
     bendersdata = SCIPbendersGetData(benders)
     PyBenders = <Benders>bendersdata
-    variable = Variable()
-    variable.var = var
-    result_dict = PyBenders.bendersgetvar(variable, probnumber)
+    PyVar = getPyVar(var)
+    result_dict = PyBenders.bendersgetvar(PyVar, probnumber)
     mappedvariable = result_dict.get("mappedvar", None)
     if mappedvariable is None:
         mappedvar[0] = NULL
     else:
-        mappedvar[0] = <SCIP_VAR*>mappedvariable.var
+        mappedvar[0] = <SCIP_VAR*>(mappedvariable.ptr())
     return SCIP_OKAY

src/pyscipopt/scip.pxd

@@ -358,6 +358,9 @@ cdef extern from "scip/scip.h":
     ctypedef struct SCIP_CONSDATA:
         pass
 
+    ctypedef struct SCIP_VARDATA:
+        pass
+
     ctypedef struct SCIP_EVENT:
         pass
 
@@ -618,6 +621,8 @@ cdef extern from "scip/scip.h":
     SCIP_Real SCIPvarGetUbLocal(SCIP_VAR* var)
     SCIP_Real SCIPvarGetObj(SCIP_VAR* var)
     SCIP_Real SCIPvarGetLPSol(SCIP_VAR* var)
+    void SCIPvarSetData(SCIP_VAR* var, SCIP_VARDATA* vardata)
+    SCIP_VARDATA* SCIPvarGetData(SCIP_VAR* var)
 
     # LP Methods
     SCIP_RETCODE SCIPgetLPColsData(SCIP* scip, SCIP_COL*** cols, int* ncols)
@@ -976,7 +981,7 @@ cdef extern from "scip/scip.h":
                                    SCIP_RETCODE (*bendersfreesub) (SCIP* scip, SCIP_BENDERS* benders, int probnumber),
                                    SCIP_BENDERSDATA* bendersdata)
     SCIP_BENDERS* SCIPfindBenders(SCIP* scip, const char* name)
-    SCIP_RETCODE SCIPactivateBenders(SCIP* scip, SCIP_BENDERS* benders)
+    SCIP_RETCODE SCIPactivateBenders(SCIP* scip, SCIP_BENDERS* benders, int nsubproblems)
     SCIP_BENDERSDATA* SCIPbendersGetData(SCIP_BENDERS* benders)
     SCIP_RETCODE SCIPcreateBendersDefault(SCIP* scip, SCIP** subproblems, int nsubproblems)
     int SCIPbendersGetNSubproblems(SCIP_BENDERS* benders);
@@ -991,6 +996,9 @@ cdef extern from "scip/scip.h":
     int SCIPgetNActiveBenders(SCIP* scip)
     SCIP_BENDERS** SCIPgetBenders(SCIP* scip)
     void SCIPbendersUpdateSubproblemLowerbound(SCIP_BENDERS* benders, int probnumber, SCIP_Real lowerbound)
+    SCIP_RETCODE SCIPaddBendersSubproblem(SCIP* scip, SCIP_BENDERS* benders, SCIP* subproblem)
+    SCIP_RETCODE SCIPgetBendersMasterVar(SCIP* scip, SCIP_BENDERS* benders, SCIP_VAR* var, SCIP_VAR** mappedvar)
+    SCIP_RETCODE SCIPgetBendersSubproblemVar(SCIP* scip, SCIP_BENDERS* benders, SCIP_VAR* var, SCIP_VAR** mappedvar, int probnumber)
 
     SCIP_RETCODE SCIPbranchVar(SCIP* scip,
                                 SCIP_VAR* var,

src/pyscipopt/scip.pyx

@@ -962,6 +962,9 @@ cdef class Model:
             PY_SCIP_CALL(SCIPaddVar(self._scip, scip_var))
 
         pyVar = Variable.create(scip_var)
+
+        #setting the variable data
+        SCIPvarSetData(scip_var, <SCIP_VARDATA*>pyVar)
         PY_SCIP_CALL(SCIPreleaseVar(self._scip, &scip_var))
         return pyVar
 
@@ -1049,8 +1052,8 @@ cdef class Model:
         cdef SCIP_Bool tightened
         PY_SCIP_CALL(SCIPtightenVarUb(self._scip, var.var, ub, force, &infeasible, &tightened))
         return infeasible, tightened
-    
-    
+
+
     def tightenVarUbGlobal(self, Variable var, ub, force=False):
         """Tighten the global upper bound, if the bound is tighter.
 
@@ -1066,7 +1069,7 @@ cdef class Model:
         cdef SCIP_Bool tightened
         PY_SCIP_CALL(SCIPtightenVarUbGlobal(self._scip, var.var, ub, force, &infeasible, &tightened))
         return infeasible, tightened
-    
+
     def tightenVarLbGlobal(self, Variable var, lb, force=False):
         """Tighten the global upper bound, if the bound is tighter.
 
@@ -1193,6 +1196,10 @@ cdef class Model:
         """Retrieve number of variables in the problems"""
         return SCIPgetNVars(self._scip)
 
+    def getNConss(self):
+        """Retrieve the number of constraints."""
+        return SCIPgetNConss(self._scip)
+
     def updateNodeLowerbound(self, Node node, lb):
         """if given value is larger than the node's lower bound (in transformed problem),
         sets the node's lower bound to the new value
@@ -2453,6 +2460,57 @@ cdef class Model:
         for d in lowerbounds.keys():
             SCIPbendersUpdateSubproblemLowerbound(_benders, d, lowerbounds[d])
 
+    def activateBenders(self, str name, int nsubproblems):
+        """Activates the Benders' decomposition plugin with the input name
+
+        Keyword arguments:
+        name -- the name of the Benders' decomposition plugin
+        nsubproblems -- the number of subproblems in the Benders' decomposition
+        """
+        n = str_conversion(name)
+        cdef SCIP_BENDERS* benders
+        benders = SCIPfindBenders(self._scip, n)
+        PY_SCIP_CALL(SCIPactivateBenders(self._scip, benders, nsubproblems))
+
+    def addBendersSubproblem(self, str name, subproblem):
+        """adds a subproblem to the Benders' decomposition given by the input
+        name.
+
+        Keyword arguments:
+        name -- the Benders' decomposition that the subproblem is added to
+        subproblem --  the subproblem to add to the decomposition
+        """
+        cdef SCIP_BENDERS* benders
+        n = str_conversion(name)
+        benders = SCIPfindBenders(self._scip, n)
+        PY_SCIP_CALL(SCIPaddBendersSubproblem(self._scip, benders, (<Model>subproblem)._scip))
+
+    def getBendersVar(self, Variable var, Benders benders = None, probnumber = -1):
+        """Returns the variable for the subproblem or master problem
+        depending on the input probnumber
+
+        Keyword arguments:
+        var -- the source variable for which the target variable is requested
+        benders -- the Benders' decomposition to which the subproblem variables belong to
+        probnumber -- the problem number for which the target variable belongs, -1 for master problem
+        """
+        cdef SCIP_BENDERS* _benders
+        cdef SCIP_VAR* _mappedvar
+
+        if benders is None:
+            _benders = SCIPfindBenders(self._scip, "default")
+        else:
+            n = str_conversion(benders.name)
+            _benders = SCIPfindBenders(self._scip, n)
+
+        if probnumber == -1:
+            PY_SCIP_CALL(SCIPgetBendersMasterVar(self._scip, _benders, var.var, &_mappedvar))
+        else:
+            PY_SCIP_CALL(SCIPgetBendersSubproblemVar(self._scip, _benders, var.var, &_mappedvar, probnumber))
+
+        return Variable.create(_mappedvar)
+
+
     def includeEventhdlr(self, Eventhdlr eventhdlr, name, desc):
         """Include an event handler.