#region License Information /* HeuristicLab * Copyright (C) 2002-2019 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.Collections.Generic; using System.Linq; using HeuristicLab.Common; using HeuristicLab.Core; using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding; using HeuristicLab.Parameters; using HEAL.Attic; namespace HeuristicLab.Problems.DataAnalysis.Symbolic.Regression { [StorableType("75843B4E-C69C-423A-87BD-A64619D380BB")] [Item("SymbolicRegressionPruningOperator", "An operator which prunes symbolic regression trees.")] public class SymbolicRegressionPruningOperator : SymbolicDataAnalysisExpressionPruningOperator { private const string EvaluatorParameterName = "Evaluator"; #region parameter properties public ILookupParameter EvaluatorParameter { get { return (ILookupParameter)Parameters[EvaluatorParameterName]; } } #endregion protected SymbolicRegressionPruningOperator(SymbolicRegressionPruningOperator original, Cloner cloner) : base(original, cloner) { } public override IDeepCloneable Clone(Cloner cloner) { return new SymbolicRegressionPruningOperator(this, cloner); } [StorableConstructor] protected SymbolicRegressionPruningOperator(StorableConstructorFlag _) : base(_) { } public SymbolicRegressionPruningOperator(ISymbolicDataAnalysisSolutionImpactValuesCalculator impactValuesCalculator) : base(impactValuesCalculator) { Parameters.Add(new LookupParameter(EvaluatorParameterName)); } [StorableHook(HookType.AfterDeserialization)] private void AfterDeserialization() { // BackwardsCompatibility3.3 #region Backwards compatible code, remove with 3.4 base.ImpactValuesCalculator = new SymbolicRegressionSolutionImpactValuesCalculator(); if (!Parameters.ContainsKey(EvaluatorParameterName)) { Parameters.Add(new LookupParameter(EvaluatorParameterName)); } #endregion } protected override ISymbolicDataAnalysisModel CreateModel(ISymbolicExpressionTree tree, ISymbolicDataAnalysisExpressionTreeInterpreter interpreter, IDataAnalysisProblemData problemData, DoubleLimit estimationLimits) { var regressionProblemData = (IRegressionProblemData)problemData; return new SymbolicRegressionModel(regressionProblemData.TargetVariable, tree, interpreter, estimationLimits.Lower, estimationLimits.Upper); } protected override double Evaluate(IDataAnalysisModel model) { var regressionModel = (ISymbolicRegressionModel)model; var regressionProblemData = (IRegressionProblemData)ProblemDataParameter.ActualValue; var evaluator = EvaluatorParameter.ActualValue; var fitnessEvaluationPartition = FitnessCalculationPartitionParameter.ActualValue; var rows = Enumerable.Range(fitnessEvaluationPartition.Start, fitnessEvaluationPartition.Size); return evaluator.Evaluate(this.ExecutionContext, regressionModel.SymbolicExpressionTree, regressionProblemData, rows); } public static ISymbolicExpressionTree Prune(ISymbolicExpressionTree tree, SymbolicRegressionSolutionImpactValuesCalculator impactValuesCalculator, ISymbolicDataAnalysisExpressionTreeInterpreter interpreter, IRegressionProblemData problemData, DoubleLimit estimationLimits, IEnumerable rows, double nodeImpactThreshold = 0.0, bool pruneOnlyZeroImpactNodes = false) { var clonedTree = (ISymbolicExpressionTree)tree.Clone(); var model = new SymbolicRegressionModel(problemData.TargetVariable, clonedTree, interpreter, estimationLimits.Lower, estimationLimits.Upper); var nodes = clonedTree.Root.GetSubtree(0).GetSubtree(0).IterateNodesPrefix().ToList(); // skip the nodes corresponding to the ProgramRootSymbol and the StartSymbol double qualityForImpactsCalculation = double.NaN; // pass a NaN value initially so the impact calculator will calculate the quality for (int i = 0; i < nodes.Count; ++i) { var node = nodes[i]; if (node is ConstantTreeNode) continue; double impactValue, replacementValue; double newQualityForImpactsCalculation; impactValuesCalculator.CalculateImpactAndReplacementValues(model, node, problemData, rows, out impactValue, out replacementValue, out newQualityForImpactsCalculation, qualityForImpactsCalculation); if (pruneOnlyZeroImpactNodes && !impactValue.IsAlmost(0.0)) continue; if (!pruneOnlyZeroImpactNodes && impactValue > nodeImpactThreshold) 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 qualityForImpactsCalculation = newQualityForImpactsCalculation; } return model.SymbolicExpressionTree; } } }