Changeset 15704 for branches/1614_GeneralizedQAP/HeuristicLab.Problems.GeneralizedQuadraticAssignment.Algorithms/3.3/GRASP

Timestamp:

02/01/18 10:25:57 (7 years ago)

Author:

abeham

Message:

#1614:

• fixed exception in case no solution could be found
• fixed behavior in GRASP regarding infeasible solutions

File:

• branches/1614_GeneralizedQAP/HeuristicLab.Problems.GeneralizedQuadraticAssignment.Algorithms/3.3/GRASP/GRASP.cs (modified) (3 diffs)

branches/1614_GeneralizedQAP/HeuristicLab.Problems.GeneralizedQuadraticAssignment.Algorithms/3.3/GRASP/GRASP.cs

@@ -170 +170 @@
         IntegerVector pi_prime_vec = null;
         try {
-          pi_prime_vec = GreedyRandomizedSolutionCreator.CreateSolution(Context.Random, Problem.ProblemInstance, 1000, false, cancellationToken);
+          pi_prime_vec = GreedyRandomizedSolutionCreator.CreateSolution(Context.Random, Problem.ProblemInstance, 10, true, cancellationToken);
         } catch (OperationCanceledException) { break; }
 
@@ -204 +204 @@
                                           .OrderByDescending(x => similarities[x.Index]) // line 14 in Algorithm 1
                                           .FirstOrDefault();
-              if (replacement != null) { 
+              if (replacement != null) {
                 Context.ReplaceAtPopulation(replacement.Index, Context.ToScope(pi_prime, fitness)); // line 14 in Algorithm 1
               }
@@ -223 +223 @@
             Context.BestQuality = fitness;
             Context.BestSolution = (GQAPSolution)pi_prime.Clone();
+          }
+        } else if (Context.PopulationCount == 0) {
+          // Book-keeping
+          // pi_prime_vec is not feasible, but no other feasible solution has been found so far
+          var eval = Problem.ProblemInstance.Evaluate(pi_prime_vec);
+          Context.EvaluatedSolutions++;
+          var fit = Problem.ProblemInstance.ToSingleObjective(eval);
+          if (double.IsNaN(Context.BestQuality) || fit < Context.BestQuality) {
+            Context.BestQuality = fit;
+            Context.BestSolution = new GQAPSolution(pi_prime_vec, eval);
           }
         }