Changeset 16616 for branches/2925_AutoDiffForDynamicalModels/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding

Timestamp:

02/20/19 07:43:25 (6 years ago)

Author:

gkronber

Message:

#2925 added crossover probability (important for multi-encoding in this case), re-added scaling of targets

File:

• branches/2925_AutoDiffForDynamicalModels/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.4/Crossovers/SubtreeCrossover.cs (modified) (5 diffs)

branches/2925_AutoDiffForDynamicalModels/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.4/Crossovers/SubtreeCrossover.cs

@@ -43 +43 @@
     private const string MaximumSymbolicExpressionTreeLengthParameterName = "MaximumSymbolicExpressionTreeLength";
     private const string MaximumSymbolicExpressionTreeDepthParameterName = "MaximumSymbolicExpressionTreeDepth";
+    private const string CrossoverProbabilityParameterName = "CrossoverProbability";
 
     #region Parameter Properties
@@ -53 +54 @@
     public IValueLookupParameter<IntValue> MaximumSymbolicExpressionTreeDepthParameter {
       get { return (IValueLookupParameter<IntValue>)Parameters[MaximumSymbolicExpressionTreeDepthParameterName]; }
+    }
+    public IValueParameter<PercentValue> CrossoverProbabilityParameter {
+      get { return (IValueParameter<PercentValue>)Parameters[CrossoverProbabilityParameterName]; }
     }
     #endregion
@@ -64 +68 @@
     public IntValue MaximumSymbolicExpressionTreeDepth {
       get { return MaximumSymbolicExpressionTreeDepthParameter.ActualValue; }
+    }
+    public PercentValue CrossoverProbability {
+      get { return CrossoverProbabilityParameter.Value; }
     }
     #endregion
@@ -74 +81 @@
       Parameters.Add(new ValueLookupParameter<IntValue>(MaximumSymbolicExpressionTreeDepthParameterName, "The maximal depth of the symbolic expression tree (a tree with one node has depth = 0)."));
       Parameters.Add(new ValueLookupParameter<PercentValue>(InternalCrossoverPointProbabilityParameterName, "The probability to select an internal crossover point (instead of a leaf node).", new PercentValue(0.9)));
+      Parameters.Add(new ValueParameter<PercentValue>(CrossoverProbabilityParameterName, "The probability to apply crossover (default 100%).", new PercentValue(1)));
     }
 
     public override IDeepCloneable Clone(Cloner cloner) {
       return new SubtreeCrossover(this, cloner);
+    }
+
+    [StorableHook(HookType.AfterDeserialization)]
+    private void AfterDeserialization() {
+      if (!Parameters.ContainsKey(CrossoverProbabilityParameterName)) {
+        Parameters.Add(new ValueParameter<PercentValue>(CrossoverProbabilityParameterName, "The probability to apply crossover (default 100%).", new PercentValue(1)));
+      }
     }
 
@@ -83 +98 @@
       ISymbolicExpressionTree parent0, ISymbolicExpressionTree parent1) {
       return Cross(random, parent0, parent1, InternalCrossoverPointProbability.Value,
-        MaximumSymbolicExpressionTreeLength.Value, MaximumSymbolicExpressionTreeDepth.Value);
+        MaximumSymbolicExpressionTreeLength.Value, MaximumSymbolicExpressionTreeDepth.Value, CrossoverProbability.Value);
     }
 
     public static ISymbolicExpressionTree Cross(IRandom random,
       ISymbolicExpressionTree parent0, ISymbolicExpressionTree parent1,
-      double internalCrossoverPointProbability, int maxTreeLength, int maxTreeDepth) {
+      double internalCrossoverPointProbability, int maxTreeLength, int maxTreeDepth, double crossoverProbability = 1.0) {
+      if (random.NextDouble() >= crossoverProbability) {
+        return random.NextDouble() < 0.5 ? parent0 : parent1;
+      }
+
       // select a random crossover point in the first parent 
       CutPoint crossoverPoint0;