#region License Information /* HeuristicLab * Copyright (C) 2002-2015 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 . */ #endregion using System.Linq; using HeuristicLab.Common; using HeuristicLab.Core; using HeuristicLab.Data; using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding; using HeuristicLab.Operators; using HeuristicLab.Parameters; using HeuristicLab.Persistence.Default.CompositeSerializers.Storable; namespace HeuristicLab.Problems.DataAnalysis.Symbolic { [StorableClass] [Item("SymbolicExpressionTreePruningOperator", "An operator that replaces introns with constant values in a symbolic expression tree.")] public abstract class SymbolicDataAnalysisExpressionPruningOperator : SingleSuccessorOperator { #region parameter names private const string ProblemDataParameterName = "ProblemData"; private const string SymbolicDataAnalysisModelParameterName = "SymbolicDataAnalysisModel"; private const string ImpactValuesCalculatorParameterName = "ImpactValuesCalculator"; private const string PrunedSubtreesParameterName = "PrunedSubtrees"; private const string PrunedTreesParameterName = "PrunedTrees"; private const string FitnessCalculationPartitionParameterName = "FitnessCalculationPartition"; private const string NodeImpactThresholdParameterName = "ImpactThreshold"; private const string PruneOnlyZeroImpactNodesParameterName = "PruneOnlyZeroImpactNodes"; private const string SymbolicExpressionTreeParameterName = "SymbolicExpressionTree"; // the tree to be pruned private const string QualityParameterName = "Quality"; // the quality private const string EstimationLimitsParameterName = "EstimationLimits"; private const string InterpreterParameterName = "SymbolicExpressionTreeInterpreter"; #endregion #region parameter properties public ILookupParameter SymbolicExpressionTreeParameter { get { return (ILookupParameter)Parameters[SymbolicExpressionTreeParameterName]; } } public ILookupParameter QualityParameter { get { return (ILookupParameter)Parameters[QualityParameterName]; } } public ILookupParameter ProblemDataParameter { get { return (ILookupParameter)Parameters[ProblemDataParameterName]; } } public IValueParameter ImpactValuesCalculatorParameter { get { return (IValueParameter)Parameters[ImpactValuesCalculatorParameterName]; } } public ILookupParameter FitnessCalculationPartitionParameter { get { return (ILookupParameter)Parameters[FitnessCalculationPartitionParameterName]; } } public ILookupParameter PrunedSubtreesParameter { get { return (ILookupParameter)Parameters[PrunedSubtreesParameterName]; } } public ILookupParameter PrunedTreesParameter { get { return (ILookupParameter)Parameters[PrunedTreesParameterName]; } } public IFixedValueParameter NodeImpactThresholdParameter { get { return (IFixedValueParameter)Parameters[NodeImpactThresholdParameterName]; } } public IFixedValueParameter PruneOnlyZeroImpactNodesParameter { get { return (IFixedValueParameter)Parameters[PruneOnlyZeroImpactNodesParameterName]; } } public ILookupParameter EstimationLimitsParameter { get { return (ILookupParameter)Parameters[EstimationLimitsParameterName]; } } public ILookupParameter InterpreterParameter { get { return (ILookupParameter)Parameters[InterpreterParameterName]; } } #endregion #region properties protected IDataAnalysisProblemData ProblemData { get { return ProblemDataParameter.ActualValue; } } protected ISymbolicDataAnalysisSolutionImpactValuesCalculator ImpactValuesCalculator { get { return ImpactValuesCalculatorParameter.Value; } } protected IntRange FitnessCalculationPartition { get { return FitnessCalculationPartitionParameter.ActualValue; } } protected bool PruneOnlyZeroImpactNodes { get { return PruneOnlyZeroImpactNodesParameter.Value.Value; } set { PruneOnlyZeroImpactNodesParameter.Value.Value = value; } } protected double NodeImpactThreshold { get { return NodeImpactThresholdParameter.Value.Value; } set { NodeImpactThresholdParameter.Value.Value = value; } } protected ISymbolicExpressionTree SymbolicExpressionTree { get { return SymbolicExpressionTreeParameter.ActualValue; } } protected DoubleValue Quality { get { return QualityParameter.ActualValue; } } protected DoubleLimit EstimationLimits { get { return EstimationLimitsParameter.ActualValue; } } protected ISymbolicDataAnalysisExpressionTreeInterpreter Interpreter { get { return InterpreterParameter.ActualValue; } } #endregion [StorableConstructor] protected SymbolicDataAnalysisExpressionPruningOperator(bool deserializing) : base(deserializing) { } protected SymbolicDataAnalysisExpressionPruningOperator(SymbolicDataAnalysisExpressionPruningOperator original, Cloner cloner) : base(original, cloner) { } protected SymbolicDataAnalysisExpressionPruningOperator(ISymbolicDataAnalysisSolutionImpactValuesCalculator impactValuesCalculator) { #region add parameters Parameters.Add(new LookupParameter(ProblemDataParameterName)); Parameters.Add(new LookupParameter(SymbolicDataAnalysisModelParameterName)); Parameters.Add(new LookupParameter(FitnessCalculationPartitionParameterName)); Parameters.Add(new LookupParameter(PrunedSubtreesParameterName, "A counter of how many subtrees were replaced.")); Parameters.Add(new LookupParameter(PrunedTreesParameterName, "A counter of how many trees were pruned.")); Parameters.Add(new FixedValueParameter(PruneOnlyZeroImpactNodesParameterName, "Specify whether or not only zero impact nodes should be pruned.")); Parameters.Add(new FixedValueParameter(NodeImpactThresholdParameterName, "Specifies an impact value threshold below which nodes should be pruned.")); Parameters.Add(new LookupParameter(EstimationLimitsParameterName)); Parameters.Add(new LookupParameter(InterpreterParameterName)); Parameters.Add(new LookupParameter(SymbolicExpressionTreeParameterName)); Parameters.Add(new LookupParameter(QualityParameterName)); Parameters.Add(new ValueParameter(ImpactValuesCalculatorParameterName, impactValuesCalculator)); #endregion } protected abstract ISymbolicDataAnalysisModel CreateModel(ISymbolicExpressionTree tree, ISymbolicDataAnalysisExpressionTreeInterpreter interpreter, IDataAnalysisProblemData problemData, DoubleLimit estimationLimits); protected abstract double Evaluate(IDataAnalysisModel model); public override IOperation Apply() { var model = CreateModel(SymbolicExpressionTree, Interpreter, ProblemData, EstimationLimits); var nodes = SymbolicExpressionTree.Root.GetSubtree(0).GetSubtree(0).IterateNodesPrefix().ToList(); var rows = Enumerable.Range(FitnessCalculationPartition.Start, FitnessCalculationPartition.Size); var prunedSubtrees = 0; var prunedTrees = 0; double quality = Evaluate(model); for (int i = 0; i < nodes.Count; ++i) { var node = nodes[i]; if (node is ConstantTreeNode) continue; double impactValue, replacementValue; ImpactValuesCalculator.CalculateImpactAndReplacementValues(model, node, ProblemData, rows, out impactValue, out replacementValue, quality); if (PruneOnlyZeroImpactNodes) { if (!impactValue.IsAlmost(0.0)) continue; } else if (NodeImpactThreshold < impactValue) { continue; } var constantNode = (ConstantTreeNode)node.Grammar.GetSymbol("Constant").CreateTreeNode(); constantNode.Value = replacementValue; ReplaceWithConstant(node, constantNode); i += node.GetLength() - 1; // skip subtrees under the node that was folded quality -= impactValue; prunedSubtrees++; } if (prunedSubtrees > 0) prunedTrees = 1; PrunedSubtreesParameter.ActualValue = new IntValue(prunedSubtrees); PrunedTreesParameter.ActualValue = new IntValue(prunedTrees); return base.Apply(); } public ISymbolicExpressionTree Prune(ISymbolicExpressionTree tree, ISymbolicDataAnalysisExpressionTreeInterpreter interpreter, IDataAnalysisProblemData problemData, DoubleLimit estimationLimits) { var model = CreateModel((ISymbolicExpressionTree)tree.Clone(), Interpreter, ProblemData, EstimationLimits); var nodes = SymbolicExpressionTree.Root.GetSubtree(0).GetSubtree(0).IterateNodesPrefix().ToList(); var rows = Enumerable.Range(FitnessCalculationPartition.Start, FitnessCalculationPartition.Size); double quality = Evaluate(model); for (int i = 0; i < nodes.Count; ++i) { var node = nodes[i]; if (node is ConstantTreeNode) continue; double impactValue, replacementValue; ImpactValuesCalculator.CalculateImpactAndReplacementValues(model, node, ProblemData, rows, out impactValue, out replacementValue, quality); if (PruneOnlyZeroImpactNodes) { if (!impactValue.IsAlmost(0.0)) continue; } else if (NodeImpactThreshold < impactValue) { continue; } var constantNode = (ConstantTreeNode)node.Grammar.GetSymbol("Constant").CreateTreeNode(); constantNode.Value = replacementValue; ReplaceWithConstant(node, constantNode); i += node.GetLength() - 1; // skip subtrees under the node that was folded quality -= impactValue; } return model.SymbolicExpressionTree; } protected static void ReplaceWithConstant(ISymbolicExpressionTreeNode original, ISymbolicExpressionTreeNode replacement) { var parent = original.Parent; var i = parent.IndexOfSubtree(original); parent.RemoveSubtree(i); parent.InsertSubtree(i, replacement); } } }