Changeset 8319 for branches/ScatterSearch (trunk integration)/HeuristicLab.Problems.Knapsack/3.3/Improvers/KnapsackImprovementOperator.cs

Timestamp:

07/24/12 15:04:37 (12 years ago)

Author:

jkarder

Message:

#1331:

• applied some of the changes suggested by ascheibe in comment:32:ticket:1331
• restructured path relinking and improvement operators and similarity calculators
• fixed bug in TSPMultipleGuidesPathRelinker

File:

• branches/ScatterSearch (trunk integration)/HeuristicLab.Problems.Knapsack/3.3/Improvers/KnapsackImprovementOperator.cs (modified) (5 diffs)

branches/ScatterSearch (trunk integration)/HeuristicLab.Problems.Knapsack/3.3/Improvers/KnapsackImprovementOperator.cs

@@ -35 +35 @@
   /// An operator that improves knapsack solutions.
   /// </summary>
+  /// <remarks>
+  /// It is implemented as described in Laguna, M. and Martí, R. (2003). Scatter Search: Methodology and Implementations in C. Operations Research/Computer Science Interfaces Series, Vol. 24. Springer.<br />
+  /// The operator first orders the elements of the knapsack according to their value-to-weight ratio, then, if the solution is not feasible, removes the element with the lowest ratio until the solution is feasible and tries to add new elements with the best ratio that are not already included yet until the knapsack is full.
+  /// </remarks>
   [Item("KnapsackImprovementOperator", "An operator that improves knapsack solutions.")]
   [StorableClass]
-  public sealed class KnapsackImprovementOperator : SingleSuccessorOperator, IImprovementOperator {
+  public sealed class KnapsackImprovementOperator : SingleSuccessorOperator, ISingleObjectiveImprovementOperator {
     #region Parameter properties
     public ScopeParameter CurrentScopeParameter {
@@ -48 +52 @@
       get { return (ILookupParameter<DoubleValue>)Parameters["Penalty"]; }
     }
-    public IValueLookupParameter<IItem> TargetParameter {
-      get { return (IValueLookupParameter<IItem>)Parameters["Target"]; }
+    public IValueLookupParameter<IItem> SolutionParameter {
+      get { return (IValueLookupParameter<IItem>)Parameters["Solution"]; }
     }
     public ILookupParameter<IntArray> ValuesParameter {
@@ -90 +94 @@
       Parameters.Add(new LookupParameter<IntValue>("KnapsackCapacity", "Capacity of the Knapsack."));
       Parameters.Add(new LookupParameter<DoubleValue>("Penalty", "The penalty value for each unit of overweight."));
-      Parameters.Add(new ValueLookupParameter<IItem>("Target", "This parameter is used for name translation only."));
+      Parameters.Add(new ValueLookupParameter<IItem>("Solution", "The solution to be improved. This parameter is used for name translation only."));
       Parameters.Add(new LookupParameter<IntArray>("Values", "The values of the items."));
       Parameters.Add(new LookupParameter<IntArray>("Weights", "The weights of the items."));
@@ -101 +105 @@
 
     public override IOperation Apply() {
-      BinaryVector sol = CurrentScope.Variables[TargetParameter.ActualName].Value as BinaryVector;
+      BinaryVector sol = CurrentScope.Variables[SolutionParameter.ActualName].Value as BinaryVector;
       if (sol == null)
         throw new ArgumentException("Cannot improve solution because it has the wrong type.");
@@ -143 +147 @@
       }
 
-      CurrentScope.Variables[TargetParameter.ActualName].Value = sol;
+      CurrentScope.Variables[SolutionParameter.ActualName].Value = sol;
       CurrentScope.Variables.Add(new Variable("LocalEvaluatedSolutions", new IntValue(evaluatedSolutions)));