source: branches/GP-MoveOperators/HeuristicLab.Problems.DataAnalysis.Symbolic.Regression/3.4/ReplaceBranchMoveMaker.cs @ 8214

#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2012 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
using HeuristicLab.Operators;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Problems.DataAnalysis.Symbolic.Regression {
  [Item("ReplaceBranchMoveMaker", "")]
  [StorableClass]
  public class ReplaceBranchMoveMaker : SingleSuccessorOperator, ISymbolicExpressionTreeMoveOperator, IMoveMaker {
    public override bool CanChangeName {
      get { return false; }
    }
    public ILookupParameter<DoubleValue> QualityParameter {
      get { return (ILookupParameter<DoubleValue>)Parameters["Quality"]; }
    }
    public ILookupParameter<DoubleValue> MoveQualityParameter {
      get { return (ILookupParameter<DoubleValue>)Parameters["MoveQuality"]; }
    }
    public ILookupParameter<ReplaceBranchMove> ReplaceBranchMoveParameter {
      get { return (ILookupParameter<ReplaceBranchMove>)Parameters["ReplaceBranchMove"]; }
    }
    public ILookupParameter<ISymbolicExpressionTree> SymbolicExpressionTreeParameter {
      get { return (ILookupParameter<ISymbolicExpressionTree>)Parameters["SymbolicExpressionTree"]; }
    }

    [StorableConstructor]
    protected ReplaceBranchMoveMaker(bool deserializing) : base(deserializing) { }
    protected ReplaceBranchMoveMaker(ReplaceBranchMoveMaker original, Cloner cloner) : base(original, cloner) { }
    public ReplaceBranchMoveMaker()
      : base() {
      Parameters.Add(new LookupParameter<DoubleValue>("Quality", "The quality of the solution."));
      Parameters.Add(new LookupParameter<ReplaceBranchMove>("ReplaceBranchMove", "The move to evaluate."));
      Parameters.Add(new LookupParameter<DoubleValue>("MoveQuality", "The relative quality of the move."));
      Parameters.Add(new LookupParameter<ISymbolicExpressionTree>("SymbolicExpressionTree", "The symbolic expression tree on which the move should be applied."));
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new ReplaceBranchMoveMaker(this, cloner);
    }

    public override IOperation Apply() {
      var move = ReplaceBranchMoveParameter.ActualValue;
      DoubleValue moveQuality = MoveQualityParameter.ActualValue;
      DoubleValue quality = QualityParameter.ActualValue;

      var newNode = (ISymbolicExpressionTreeNode)move.NewBranch.Clone();
      move.Parent.RemoveSubtree(move.SubtreeIndex);
      move.Parent.InsertSubtree(move.SubtreeIndex, Scale(newNode, move.Alpha, move.Beta));

      quality.Value = moveQuality.Value;
      // update solution
      SymbolicExpressionTreeParameter.ActualValue = move.Tree;

      return base.Apply();
    }


    private Addition add = new Addition();
    private Multiplication mul = new Multiplication();
    private Constant constant = new Constant();

    private ISymbolicExpressionTreeNode Scale(ISymbolicExpressionTreeNode node, double alpha, double beta) {
      var constNode = node as ConstantTreeNode;
      if (constNode != null) {
        constNode.Value = constNode.Value * beta + alpha;
        return constNode;
      }
      var varNode = node as VariableTreeNode;
      if (varNode != null) {
        varNode.Weight = varNode.Weight * beta;
        var constAlpha = (ConstantTreeNode)constant.CreateTreeNode();
        constAlpha.Value = alpha;
        var sum = add.CreateTreeNode();
        sum.AddSubtree(varNode); sum.AddSubtree(constAlpha);
        return sum;
      }
      if (node.Symbol is Addition && node.GetSubtree(0).Symbol is Multiplication &&
        node.GetSubtree(1).Symbol is Constant && node.GetSubtree(0).GetSubtree(1).Symbol is Constant) {
        var constAlpha = node.GetSubtree(1) as ConstantTreeNode;
        var constBeta = node.GetSubtree(0).GetSubtree(1) as ConstantTreeNode;
        constAlpha.Value = beta * constAlpha.Value + alpha;
        constBeta.Value = constBeta.Value * beta;
        return node;
      } else {
        var constAlpha = (ConstantTreeNode)constant.CreateTreeNode();
        var constBeta = (ConstantTreeNode)constant.CreateTreeNode();
        constAlpha.Value = alpha;
        constBeta.Value = beta;
        var sum = add.CreateTreeNode();
        var prod = mul.CreateTreeNode();
        prod.AddSubtree(node);
        prod.AddSubtree(constBeta);
        sum.AddSubtree(prod);
        sum.AddSubtree(constAlpha);
        return sum;
      }
    }
  }
}