1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2008 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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4 | *
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5 | * This file is part of HeuristicLab.
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6 | *
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7 | * HeuristicLab is free software: you can redistribute it and/or modify
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8 | * it under the terms of the GNU General Public License as published by
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9 | * the Free Software Foundation, either version 3 of the License, or
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10 | * (at your option) any later version.
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11 | *
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12 | * HeuristicLab is distributed in the hope that it will be useful,
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 | * GNU General Public License for more details.
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16 | *
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17 | * You should have received a copy of the GNU General Public License
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18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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19 | */
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20 | #endregion
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21 |
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22 | using System;
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23 | using System.Collections.Generic;
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24 | using HeuristicLab.Core;
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25 | using HeuristicLab.DataAnalysis;
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26 | using HeuristicLab.GP.Interfaces;
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27 | using System.Xml;
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28 |
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29 | namespace HeuristicLab.GP.StructureIdentification {
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30 | /// <summary>
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31 | /// Base class for tree evaluators
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32 | /// </summary>
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33 | public abstract class TreeEvaluatorBase : ItemBase, ITreeEvaluator {
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34 | protected const double EPSILON = 1.0e-7;
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35 | protected double maxValue = double.MaxValue;
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36 | protected double minValue = double.MinValue;
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37 | private double punishmentFactor = 10.0; // we should provide a view for treeevaluators that allows to change this value
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38 |
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39 | protected class Instr {
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40 | public double d_arg0;
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41 | public short i_arg0;
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42 | public short i_arg1;
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43 | public byte arity;
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44 | public byte symbol;
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45 | }
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46 |
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47 | protected Instr[] codeArr;
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48 | protected int PC;
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49 | protected Dataset dataset;
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50 | protected int sampleIndex;
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51 |
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52 | public void PrepareForEvaluation(Dataset dataset, IFunctionTree functionTree) {
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53 | this.dataset = dataset;
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54 | codeArr = new Instr[functionTree.GetSize()];
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55 | int i = 0;
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56 | foreach (IFunctionTree tree in IteratePrefix(functionTree)) {
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57 | codeArr[i++] = TranslateToInstr(tree);
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58 | }
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59 | }
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60 |
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61 | public void PrepareForEvaluation(Dataset dataset, int targetVariable, int start, int end, IFunctionTree functionTree) {
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62 | // calculate upper and lower bounds for the estimated value (mean +/- punishmentFactor * range)
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63 | double mean = dataset.GetMean(targetVariable, start, end);
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64 | double range = dataset.GetRange(targetVariable, start, end);
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65 | maxValue = mean + punishmentFactor * range;
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66 | minValue = mean - punishmentFactor * range;
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67 | PrepareForEvaluation(dataset, functionTree);
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68 | }
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69 |
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70 | private IEnumerable<IFunctionTree> IteratePrefix(IFunctionTree functionTree) {
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71 | List<IFunctionTree> prefixForm = new List<IFunctionTree>();
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72 | prefixForm.Add(functionTree);
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73 | foreach (IFunctionTree subTree in functionTree.SubTrees) {
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74 | prefixForm.AddRange(IteratePrefix(subTree));
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75 | }
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76 | return prefixForm;
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77 | }
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78 |
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79 | private Instr TranslateToInstr(IFunctionTree tree) {
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80 | Instr instr = new Instr();
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81 | instr.arity = (byte)tree.SubTrees.Count;
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82 | instr.symbol = EvaluatorSymbolTable.MapFunction(tree.Function);
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83 | switch (instr.symbol) {
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84 | case EvaluatorSymbolTable.DIFFERENTIAL:
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85 | case EvaluatorSymbolTable.VARIABLE: {
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86 | VariableFunctionTree varTree = (VariableFunctionTree)tree;
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87 | instr.i_arg0 = (short)dataset.GetVariableIndex(varTree.VariableName);
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88 | instr.d_arg0 = varTree.Weight;
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89 | instr.i_arg1 = (short)varTree.SampleOffset;
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90 | break;
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91 | }
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92 | case EvaluatorSymbolTable.CONSTANT: {
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93 | ConstantFunctionTree constTree = (ConstantFunctionTree)tree;
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94 | instr.d_arg0 = constTree.Value;
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95 | break;
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96 | }
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97 | case EvaluatorSymbolTable.UNKNOWN: {
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98 | throw new NotSupportedException("Unknown function symbol: " + instr.symbol);
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99 | }
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100 | }
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101 | return instr;
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102 | }
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103 |
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104 | public double Evaluate(int sampleIndex) {
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105 | PC = 0;
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106 | this.sampleIndex = sampleIndex;
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107 |
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108 | double estimated = EvaluateBakedCode();
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109 | if (double.IsNaN(estimated) || double.IsInfinity(estimated)) estimated = maxValue;
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110 | else if (estimated < minValue) estimated = minValue;
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111 | else if (estimated > maxValue) estimated = maxValue;
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112 | return estimated;
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113 | }
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114 |
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115 | // skips a whole branch
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116 | protected void SkipBakedCode() {
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117 | int i = 1;
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118 | while (i > 0) {
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119 | i += codeArr[PC++].arity;
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120 | i--;
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121 | }
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122 | }
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123 |
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124 | protected abstract double EvaluateBakedCode();
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125 |
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126 | public override object Clone(IDictionary<Guid, object> clonedObjects) {
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127 | TreeEvaluatorBase clone = (TreeEvaluatorBase)base.Clone(clonedObjects);
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128 | clone.maxValue = maxValue;
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129 | clone.minValue = minValue;
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130 | clone.punishmentFactor = punishmentFactor;
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131 | return clone;
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132 | }
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133 |
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134 | public override System.Xml.XmlNode GetXmlNode(string name, System.Xml.XmlDocument document, IDictionary<Guid, IStorable> persistedObjects) {
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135 | XmlNode node = base.GetXmlNode(name, document, persistedObjects);
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136 | XmlAttribute maxValueAttribute = document.CreateAttribute("MaxPredictionValue");
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137 | XmlAttribute minValueAttribute = document.CreateAttribute("MinPredictionValue");
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138 | XmlAttribute punishmentFactorAttribute = document.CreateAttribute("PunishmentFactor");
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139 | maxValueAttribute.Value = XmlConvert.ToString(maxValue);
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140 | minValueAttribute.Value = XmlConvert.ToString(minValue);
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141 | punishmentFactorAttribute.Value = XmlConvert.ToString(punishmentFactor);
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142 |
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143 | node.Attributes.Append(punishmentFactorAttribute);
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144 | node.Attributes.Append(minValueAttribute);
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145 | node.Attributes.Append(maxValueAttribute);
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146 | return node;
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147 | }
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148 |
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149 | public override void Populate(System.Xml.XmlNode node, IDictionary<Guid, IStorable> restoredObjects) {
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150 | base.Populate(node, restoredObjects);
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151 | minValue = XmlConvert.ToDouble(node.Attributes["MinPredictionValue"].Value);
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152 | maxValue = XmlConvert.ToDouble(node.Attributes["MaxPredictionValue"].Value);
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153 | punishmentFactor = XmlConvert.ToDouble(node.Attributes["PunishmentFactor"].Value);
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154 | }
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155 | }
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156 | }
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