source: trunk/sources/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/SymbolicDataAnalysisExpressionPruningOperator.cs @ 12720

Last change on this file since 12720 was 12720, checked in by bburlacu, 6 years ago

#2359: Changed the impact calculators so that the quality value necessary for impacts calculation is calculated with a separate method. Refactored the CalculateImpactAndReplacementValues method to return the new quality in an out-parameter (adjusted method signature in interface accordingly). Added Evaluate method to the regression and classification pruning operators that re-evaluates the tree using the problem evaluator after pruning was performed.

File size: 10.7 KB
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1#region License Information
2
3/* HeuristicLab
4 * Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
5 *
6 * This file is part of HeuristicLab.
7 *
8 * HeuristicLab is free software: you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation, either version 3 of the License, or
11 * (at your option) any later version.
12 *
13 * HeuristicLab is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
20 */
21
22#endregion
23
24using System.Linq;
25using HeuristicLab.Common;
26using HeuristicLab.Core;
27using HeuristicLab.Data;
28using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
29using HeuristicLab.Operators;
30using HeuristicLab.Parameters;
31using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
32
33namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
34  [StorableClass]
35  [Item("SymbolicExpressionTreePruningOperator", "An operator that replaces introns with constant values in a symbolic expression tree.")]
36  public abstract class SymbolicDataAnalysisExpressionPruningOperator : SingleSuccessorOperator, ISymbolicExpressionTreeOperator {
37    #region parameter names
38    private const string ProblemDataParameterName = "ProblemData";
39    private const string SymbolicDataAnalysisModelParameterName = "SymbolicDataAnalysisModel";
40    private const string ImpactValuesCalculatorParameterName = "ImpactValuesCalculator";
41    private const string PrunedSubtreesParameterName = "PrunedSubtrees";
42    private const string PrunedTreesParameterName = "PrunedTrees";
43    private const string PrunedNodesParameterName = "PrunedNodes";
44    private const string FitnessCalculationPartitionParameterName = "FitnessCalculationPartition";
45    private const string NodeImpactThresholdParameterName = "ImpactThreshold";
46    private const string PruneOnlyZeroImpactNodesParameterName = "PruneOnlyZeroImpactNodes";
47    private const string SymbolicExpressionTreeParameterName = "SymbolicExpressionTree"; // the tree to be pruned
48    private const string QualityParameterName = "Quality"; // the quality
49    private const string EstimationLimitsParameterName = "EstimationLimits";
50    private const string InterpreterParameterName = "SymbolicExpressionTreeInterpreter";
51    private const string ApplyLinearScalingParameterName = "ApplyLinearScaling";
52    #endregion
53
54    #region parameter properties
55    public ILookupParameter<ISymbolicExpressionTree> SymbolicExpressionTreeParameter {
56      get { return (ILookupParameter<ISymbolicExpressionTree>)Parameters[SymbolicExpressionTreeParameterName]; }
57    }
58    public ILookupParameter<DoubleValue> QualityParameter {
59      get { return (ILookupParameter<DoubleValue>)Parameters[QualityParameterName]; }
60    }
61    public ILookupParameter<IDataAnalysisProblemData> ProblemDataParameter {
62      get { return (ILookupParameter<IDataAnalysisProblemData>)Parameters[ProblemDataParameterName]; }
63    }
64    public IValueParameter<ISymbolicDataAnalysisSolutionImpactValuesCalculator> ImpactValuesCalculatorParameter {
65      get { return (IValueParameter<ISymbolicDataAnalysisSolutionImpactValuesCalculator>)Parameters[ImpactValuesCalculatorParameterName]; }
66    }
67    public ILookupParameter<IntRange> FitnessCalculationPartitionParameter {
68      get { return (ILookupParameter<IntRange>)Parameters[FitnessCalculationPartitionParameterName]; }
69    }
70    public ILookupParameter<IntValue> PrunedSubtreesParameter {
71      get { return (ILookupParameter<IntValue>)Parameters[PrunedSubtreesParameterName]; }
72    }
73    public ILookupParameter<IntValue> PrunedTreesParameter {
74      get { return (ILookupParameter<IntValue>)Parameters[PrunedTreesParameterName]; }
75    }
76    public ILookupParameter<IntValue> PrunedNodesParameter {
77      get { return (ILookupParameter<IntValue>)Parameters[PrunedNodesParameterName]; }
78    }
79    public IFixedValueParameter<DoubleValue> NodeImpactThresholdParameter {
80      get { return (IFixedValueParameter<DoubleValue>)Parameters[NodeImpactThresholdParameterName]; }
81    }
82    public IFixedValueParameter<BoolValue> PruneOnlyZeroImpactNodesParameter {
83      get { return (IFixedValueParameter<BoolValue>)Parameters[PruneOnlyZeroImpactNodesParameterName]; }
84    }
85    public ILookupParameter<DoubleLimit> EstimationLimitsParameter {
86      get { return (ILookupParameter<DoubleLimit>)Parameters[EstimationLimitsParameterName]; }
87    }
88    public ILookupParameter<ISymbolicDataAnalysisExpressionTreeInterpreter> InterpreterParameter {
89      get { return (ILookupParameter<ISymbolicDataAnalysisExpressionTreeInterpreter>)Parameters[InterpreterParameterName]; }
90    }
91    public ILookupParameter<BoolValue> ApplyLinearScalingParameter {
92      get { return (ILookupParameter<BoolValue>)Parameters[ApplyLinearScalingParameterName]; }
93    }
94    #endregion
95
96    #region properties
97    public ISymbolicDataAnalysisSolutionImpactValuesCalculator ImpactValuesCalculator {
98      get { return ImpactValuesCalculatorParameter.Value; }
99      set { ImpactValuesCalculatorParameter.Value = value; }
100    }
101    public bool PruneOnlyZeroImpactNodes {
102      get { return PruneOnlyZeroImpactNodesParameter.Value.Value; }
103      set { PruneOnlyZeroImpactNodesParameter.Value.Value = value; }
104    }
105    public double NodeImpactThreshold {
106      get { return NodeImpactThresholdParameter.Value.Value; }
107      set { NodeImpactThresholdParameter.Value.Value = value; }
108    }
109    #endregion
110
111    [StorableConstructor]
112    protected SymbolicDataAnalysisExpressionPruningOperator(bool deserializing) : base(deserializing) { }
113    protected SymbolicDataAnalysisExpressionPruningOperator(SymbolicDataAnalysisExpressionPruningOperator original, Cloner cloner)
114      : base(original, cloner) { }
115
116    protected SymbolicDataAnalysisExpressionPruningOperator(ISymbolicDataAnalysisSolutionImpactValuesCalculator impactValuesCalculator) {
117      #region add parameters
118      Parameters.Add(new LookupParameter<IDataAnalysisProblemData>(ProblemDataParameterName));
119      Parameters.Add(new LookupParameter<ISymbolicDataAnalysisModel>(SymbolicDataAnalysisModelParameterName));
120      Parameters.Add(new LookupParameter<IntRange>(FitnessCalculationPartitionParameterName));
121      Parameters.Add(new LookupParameter<IntValue>(PrunedNodesParameterName, "A counter of how many nodes were pruned."));
122      Parameters.Add(new LookupParameter<IntValue>(PrunedSubtreesParameterName, "A counter of how many subtrees were replaced."));
123      Parameters.Add(new LookupParameter<IntValue>(PrunedTreesParameterName, "A counter of how many trees were pruned."));
124      Parameters.Add(new FixedValueParameter<BoolValue>(PruneOnlyZeroImpactNodesParameterName, "Specify whether or not only zero impact nodes should be pruned."));
125      Parameters.Add(new FixedValueParameter<DoubleValue>(NodeImpactThresholdParameterName, "Specifies an impact value threshold below which nodes should be pruned."));
126      Parameters.Add(new LookupParameter<DoubleLimit>(EstimationLimitsParameterName));
127      Parameters.Add(new LookupParameter<ISymbolicDataAnalysisExpressionTreeInterpreter>(InterpreterParameterName));
128      Parameters.Add(new LookupParameter<ISymbolicExpressionTree>(SymbolicExpressionTreeParameterName));
129      Parameters.Add(new LookupParameter<DoubleValue>(QualityParameterName));
130      Parameters.Add(new LookupParameter<BoolValue>(ApplyLinearScalingParameterName));
131      Parameters.Add(new ValueParameter<ISymbolicDataAnalysisSolutionImpactValuesCalculator>(ImpactValuesCalculatorParameterName, impactValuesCalculator));
132      #endregion
133    }
134
135    protected abstract ISymbolicDataAnalysisModel CreateModel(ISymbolicExpressionTree tree, ISymbolicDataAnalysisExpressionTreeInterpreter interpreter, IDataAnalysisProblemData problemData, DoubleLimit estimationLimits);
136
137    protected abstract double Evaluate(IDataAnalysisModel model);
138
139    public override IOperation Apply() {
140      var tree = SymbolicExpressionTreeParameter.ActualValue;
141      var problemData = ProblemDataParameter.ActualValue;
142      var fitnessCalculationPartition = FitnessCalculationPartitionParameter.ActualValue;
143      var estimationLimits = EstimationLimitsParameter.ActualValue;
144      var interpreter = InterpreterParameter.ActualValue;
145
146      var model = CreateModel(tree, interpreter, problemData, estimationLimits);
147      var nodes = tree.Root.GetSubtree(0).GetSubtree(0).IterateNodesPrefix().ToList();
148      var rows = Enumerable.Range(fitnessCalculationPartition.Start, fitnessCalculationPartition.Size).ToList();
149      var prunedSubtrees = 0;
150      var prunedTrees = 0;
151      var prunedNodes = 0;
152
153      double qualityForImpactsCalculation = double.NaN;
154
155      for (int i = 0; i < nodes.Count; ++i) {
156        var node = nodes[i];
157        if (node is ConstantTreeNode) continue;
158
159        double impactValue, replacementValue;
160        double newQualityForImpacts;
161        ImpactValuesCalculator.CalculateImpactAndReplacementValues(model, node, problemData, rows, out impactValue, out replacementValue, out newQualityForImpacts, qualityForImpactsCalculation);
162
163        if (PruneOnlyZeroImpactNodes && !impactValue.IsAlmost(0.0)) continue;
164        if (!PruneOnlyZeroImpactNodes && impactValue > NodeImpactThreshold) continue;
165
166        var constantNode = (ConstantTreeNode)node.Grammar.GetSymbol("Constant").CreateTreeNode();
167        constantNode.Value = replacementValue;
168
169        var length = node.GetLength();
170        ReplaceWithConstant(node, constantNode);
171        i += length - 1; // skip subtrees under the node that was folded
172
173        prunedSubtrees++;
174        prunedNodes += length;
175
176        qualityForImpactsCalculation = newQualityForImpacts;
177      }
178
179      if (prunedSubtrees > 0) prunedTrees = 1;
180      PrunedSubtreesParameter.ActualValue = new IntValue(prunedSubtrees);
181      PrunedTreesParameter.ActualValue = new IntValue(prunedTrees);
182      PrunedNodesParameter.ActualValue = new IntValue(prunedNodes);
183
184      if (prunedSubtrees > 0) // if nothing was pruned then there's no need to re-evaluate the tree
185        QualityParameter.ActualValue.Value = Evaluate(model);
186
187      return base.Apply();
188    }
189
190    protected static void ReplaceWithConstant(ISymbolicExpressionTreeNode original, ISymbolicExpressionTreeNode replacement) {
191      var parent = original.Parent;
192      var i = parent.IndexOfSubtree(original);
193      parent.RemoveSubtree(i);
194      parent.InsertSubtree(i, replacement);
195    }
196  }
197}
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