Changeset 14513 for branches/PushGP/HeuristicLab.Algorithms.PushGP/HeuristicLab.Algorithms.PushGP/Simplifier/RandomSimplifier.cs

Timestamp:

12/20/16 22:57:11 (7 years ago)

Author:

pkimmesw

Message:

#2665 Added Problem.ProgramSynthesis Project, Fixed Expression Issues, Fixed Code Generation

File:

• branches/PushGP/HeuristicLab.Algorithms.PushGP/HeuristicLab.Algorithms.PushGP/Simplifier/RandomSimplifier.cs (modified) (1 diff)

branches/PushGP/HeuristicLab.Algorithms.PushGP/HeuristicLab.Algorithms.PushGP/Simplifier/RandomSimplifier.cs

@@ -1 @@
-using HeuristicLab.Algorithms.PushGP.Expressions;
-using HeuristicLab.Core;
-using HeuristicLab.Random;
+namespace HeuristicLab.Algorithms.PushGP.Simplifier {
+  using System;
+  using System.Threading;
+  using HeuristicLab.Algorithms.PushGP.Data.Random;
+  using HeuristicLab.Algorithms.PushGP.Expressions;
+  using HeuristicLab.Core;
 
-namespace HeuristicLab.Algorithms.PushGP.Simplifier
-{
-    public class RandomSimplifier : ISimplifier
-    {
-        private IRandom rand = new FastRandom();
-        public int Trys { get; set; }
+  public class RandomSimplifier : ISimplifier {
+    private static readonly ThreadLocal<IRandom> random = RandomFactory.GetRandom();
 
-        public Expression Simplify(Expression program)
-        {
-            if (program.GetType() != typeof(ExecExpandExpression))
-                return program;
+    public int Trys { get; set; }
 
-            var clone = program.Clone() as ExecExpandExpression;
+    public ExecExpandExpression Simplify(ExecExpandExpression program, Predicate<ExecExpandExpression> isBetter) {
 
-            for (var i = 0; i < Trys; i++)
-            {
-                var index = rand.Next(0, clone.TotalCount - 1);
+      if (program.TotalCount == 1) {
+        return isBetter(ExecExpandExpression.Empty) ? ExecExpandExpression.Empty : program;
+      }
 
-            }
+      var copy = program.Copy();
+      var maxTrys = Math.Min(Trys, program.TotalCount - 2);
+      var sucessfullRemoves = 0;
 
-            return clone;
+      for (var i = 0; i < maxTrys; i++) {
+        var rndIndex = random.Value.Next(1, program.TotalCount - 1 - sucessfullRemoves);
+        var node = copy.GetFromTree(
+          rndIndex,
+          (super, parent, child, childIndex, parentIndex) => new {
+            Super = super,
+            Parent = parent,
+            ChildIndex = childIndex,
+            ParentIndex = parentIndex
+          });
+
+        var oldParentExpressions = node.Parent.Expressions as Expression[];
+        var newParentExpressions = RemoveAt(oldParentExpressions, node.ChildIndex);
+        var newParent = new ExecExpandExpression(newParentExpressions);
+
+        var superExpressions = (node.Super == null ? copy.Expressions : node.Super.Expressions) as Expression[];
+        superExpressions[node.ParentIndex] = newParent;
+
+        if (isBetter(copy)) {
+          sucessfullRemoves++;
+        } else {
+          superExpressions[node.ParentIndex] = node.Parent;
         }
+      }
+
+      return copy;
     }
+
+    private static T[] RemoveAt<T>(T[] source, int index) {
+      var dest = new T[source.Length - 1];
+      if (index > 0)
+        Array.Copy(source, 0, dest, 0, index);
+
+      if (index < source.Length - 1)
+        Array.Copy(source, index + 1, dest, index, source.Length - index - 1);
+
+      return dest;
+    }
+  }
 }