Fix and add isRelaxationOnly

Author: Joao-Dionisio

CHANGELOG.md

@@ -6,7 +6,7 @@
 - Added support for knapsack constraints
 - Added isPositive(), isNegative(), isFeasLE(), isFeasLT(), isFeasGE(), isFeasGT(), isHugeValue(), and tests
 - Added SCIP_LOCKTYPE, addVarLocksType(), getNLocksDown(), getNLocksUp(), getNLocksDownType(), getNLocksUpType(), and tests
-- Added SCIPvarMarkRelaxationOnly
+- Added SCIPvarMarkRelaxationOnly, SCIPvarIsRelaxationOnly
 ### Fixed
 - Raised an error when an expression is used when a variable is required
 ### Changed

src/pyscipopt/scip.pxd

@@ -818,6 +818,7 @@ cdef extern from "scip/scip.h":
     SCIP_VARDATA* SCIPvarGetData(SCIP_VAR* var)
     SCIP_Real SCIPvarGetAvgSol(SCIP_VAR* var)
     void SCIPvarMarkRelaxationOnly(SCIP_VAR* var)
+    SCIP_Bool SCIPvarIsRelaxationOnly(SCIP_VAR* var)
     SCIP_Real SCIPgetVarPseudocost(SCIP* scip, SCIP_VAR* var, SCIP_BRANCHDIR dir)
     SCIP_Real SCIPvarGetCutoffSum(SCIP_VAR* var, SCIP_BRANCHDIR dir)
     SCIP_Longint SCIPvarGetNBranchings(SCIP_VAR* var, SCIP_BRANCHDIR dir)

src/pyscipopt/scip.pxi

@@ -1690,7 +1690,24 @@ cdef class Variable(Expr):
         None
 
         """
-        PY_SCIP_CALL(SCIPvarMarkRelaxationOnly(self.scip_var))
+        SCIPvarMarkRelaxationOnly(self.scip_var)
+    
+    def isRelaxationOnly(self):
+        """
+        returns whether a variable has been introduced to define a relaxation
+
+        These variables are only valid for the current SCIP solve round, they are not contained in any (checked)
+        constraints, but may be used in cutting planes, for example. Relaxation-only variables are not copied 
+        by SCIPcopyVars and cuts that contain these variables are not added as linear constraints when 
+        restarting or transferring information from a copied SCIP to a SCIP. Also conflicts with relaxation-only
+        variables are not generated at the moment. Relaxation-only variables do not appear in the objective.
+
+        Returns
+        -------
+        bool
+
+        """
+        return SCIPvarIsRelaxationOnly(self.scip_var)
 
     def getNLocksDown(self):
         """