Add getConsVals

Author: Joao-Dionisio

CHANGELOG.md

@@ -9,6 +9,7 @@
 - Added addMatrixConsIndicator(), and tests
 - Added SCIPvarMarkRelaxationOnly, SCIPvarIsRelaxationOnly, SCIPvarMarkDeletable, SCIPvarIsDeletable, and tests
 - Wrapped SCIPgetNLPBranchCands
+- Added getConsVals, generalized getRhs, and tests
 ### Fixed
 - Raised an error when an expression is used when a variable is required
 ### Changed

src/pyscipopt/scip.pxd

@@ -858,6 +858,7 @@ cdef extern from "scip/scip.h":
     SCIP_RETCODE SCIPtransformCons(SCIP* scip, SCIP_CONS* cons, SCIP_CONS** transcons)
     SCIP_RETCODE SCIPgetTransformedCons(SCIP* scip, SCIP_CONS* cons, SCIP_CONS** transcons)
     SCIP_RETCODE SCIPgetConsVars(SCIP* scip, SCIP_CONS* cons, SCIP_VAR** vars, int varssize, SCIP_Bool* success)
+    SCIP_RETCODE SCIPgetConsVals(SCIP* scip, SCIP_CONS* cons, SCIP_Real* vals, int valssize, SCIP_Bool* success)
     SCIP_RETCODE SCIPgetConsNVars(SCIP* scip, SCIP_CONS* cons, int* nvars, SCIP_Bool* success)
     SCIP_CONS** SCIPgetConss(SCIP* scip)
     const char* SCIPconsGetName(SCIP_CONS* cons)

src/pyscipopt/scip.pxi

@@ -6035,6 +6035,31 @@ cdef class Model:
                 vars.append(var)
 
         return vars
+    
+    def getConsVals(self, Constraint constraint):
+        """
+        Returns the value array of an arbitrary SCIP constraint that can be represented as a single linear constraint.
+
+        Parameters
+        ----------
+        constraint : Constraint
+            Constraint to get the values from.
+
+        Returns
+        -------
+        list of float
+
+        """
+        cdef SCIP_Real* vals
+        cdef int nvars
+        cdef SCIP_Bool success
+        cdef int i
+
+        nvars = self.getConsNVars(constraint)
+        vals = <SCIP_Real*> malloc(nvars * sizeof(SCIP_Real))
+        PY_SCIP_CALL(SCIPgetConsVals(self._scip, constraint.scip_cons, vals, nvars*sizeof(SCIP_Real), &success))
+
+        return [vals[i] for i in range(nvars)]
 
     def getNVarsAnd(self, Constraint and_cons):
         """
@@ -7275,6 +7300,8 @@ cdef class Model:
             return SCIPgetRhsLinear(self._scip, cons.scip_cons)
         elif constype == 'nonlinear':
             return SCIPgetRhsNonlinear(cons.scip_cons)
+        elif constype == 'knapsack':
+            return SCIPgetCapacityKnapsack(self._scip, cons.scip_cons)
         else:
             raise Warning("method cannot be called for constraints of type " + constype)
 

tests/test_cons.py

@@ -27,6 +27,22 @@ def test_getConsVars():
     c = m.addCons(quicksum(x[i] for i in x) <= 1)
     assert m.getConsVars(c) == [x[i] for i in x]
 
+def test_getConsVals():
+    n_vars = 100
+    m = Model()
+    x = {}
+    for i in range(n_vars):
+        x[i] = m.addVar("%i" % i, vtype="B")
+
+    c1 = m.addCons(quicksum(x[i] for i in x) <= 1)
+    c2 = m.addConsKnapsack([x[i] for i in x], [1]*n_vars, 10)
+    vals1 = m.getConsVals(c1)
+    vals2 = m.getConsVals(c2)
+
+    assert len(vals1) == n_vars
+    assert all(isinstance(v, float) for v in vals1)
+    assert len(vals2) == n_vars
+    assert all(isinstance(v, float) for v in vals2)
 
 def test_constraint_option_setting():
     m = Model()
@@ -266,6 +282,7 @@ def test_cons_knapsack():
     m.chgCapacityKnapsack(knapsack_cons, 5)
 
     assert m.getCapacityKnapsack(knapsack_cons) == 5
+    assert m.getRhs(knapsack_cons) == 5
 
     m.addCoefKnapsack(knapsack_cons, z, 3)
     weights = m.getWeightsKnapsack(knapsack_cons)