Changeset 17490

Timestamp:

04/02/20 09:40:32 (5 years ago)

Author:

gkronber

Message:

#3067: add crossover probability for subtree crossover and initialized it to 100%

File:

• trunk/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.4/Crossovers/SubtreeCrossover.cs (modified) (6 diffs)

trunk/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 IFixedValueParameter<DoubleValue> CrossoverProbabilityParameter {
+      get { return (IFixedValueParameter<DoubleValue>)Parameters[CrossoverProbabilityParameterName]; }
     }
     #endregion
@@ -64 +68 @@
     public IntValue MaximumSymbolicExpressionTreeDepth {
       get { return MaximumSymbolicExpressionTreeDepthParameter.ActualValue; }
+    }
+    public double CrossoverProbability {
+      get { return CrossoverProbabilityParameter.Value.Value; }
+      set { CrossoverProbabilityParameter.Value.Value = value; }
     }
     #endregion
@@ -74 +82 @@
       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 FixedValueParameter<DoubleValue>(CrossoverProbabilityParameterName, "", new DoubleValue(1)));
+    }
+
+    [StorableHook(HookType.AfterDeserialization)]
+    private void AfterDeserialization() {
+      if (!Parameters.ContainsKey(CrossoverProbabilityParameterName)) {
+        Parameters.Add(new FixedValueParameter<DoubleValue>(CrossoverProbabilityParameterName, "", new DoubleValue(1)));
+      }
     }
 
@@ -82 +98 @@
     public override ISymbolicExpressionTree Crossover(IRandom random,
       ISymbolicExpressionTree parent0, ISymbolicExpressionTree parent1) {
-      return Cross(random, parent0, parent1, InternalCrossoverPointProbability.Value,
+      return Cross(random, parent0, parent1, CrossoverProbability, InternalCrossoverPointProbability.Value,
         MaximumSymbolicExpressionTreeLength.Value, MaximumSymbolicExpressionTreeDepth.Value);
     }
@@ -88 +104 @@
     public static ISymbolicExpressionTree Cross(IRandom random,
       ISymbolicExpressionTree parent0, ISymbolicExpressionTree parent1,
+      double probability,
       double internalCrossoverPointProbability, int maxTreeLength, int maxTreeDepth) {
+      if (random.NextDouble() >= probability) return random.NextDouble() < 0.5 ? parent0 : parent1;
       // select a random crossover point in the first parent 
       CutPoint crossoverPoint0;