1 | #region License Information
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2 |
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3 | /* HeuristicLab
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4 | * Copyright (C) Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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5 | *
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6 | * This file is part of HeuristicLab.
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7 | *
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8 | * HeuristicLab is free software: you can redistribute it and/or modify
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9 | * it under the terms of the GNU General Public License as published by
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10 | * the Free Software Foundation, either version 3 of the License, or
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11 | * (at your option) any later version.
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12 | *
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13 | * HeuristicLab is distributed in the hope that it will be useful,
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14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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16 | * GNU General Public License for more details.
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17 | *
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18 | * You should have received a copy of the GNU General Public License
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19 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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20 | */
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21 |
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22 | #endregion
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23 |
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24 | using System;
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25 | using System.Collections.Generic;
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26 | using System.Linq;
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27 | using HeuristicLab.Common;
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28 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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29 |
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30 | namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
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31 | /// <summary>
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32 | /// Simplifier for symbolic expressions
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33 | /// </summary>
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34 | public class VectorTreeSimplifier {
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35 | private static readonly Addition addSymbol = new Addition();
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36 | private static readonly Multiplication mulSymbol = new Multiplication();
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37 | private static readonly Division divSymbol = new Division();
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38 | private static readonly Constant constSymbol = new Constant();
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39 | private static readonly Absolute absSymbol = new Absolute();
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40 | private static readonly Logarithm logSymbol = new Logarithm();
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41 | private static readonly Exponential expSymbol = new Exponential();
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42 | private static readonly Root rootSymbol = new Root();
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43 | private static readonly Square sqrSymbol = new Square();
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44 | private static readonly SquareRoot sqrtSymbol = new SquareRoot();
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45 | private static readonly AnalyticQuotient aqSymbol = new AnalyticQuotient();
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46 | private static readonly Cube cubeSymbol = new Cube();
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47 | private static readonly CubeRoot cubeRootSymbol = new CubeRoot();
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48 | private static readonly Power powSymbol = new Power();
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49 | private static readonly Sine sineSymbol = new Sine();
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50 | private static readonly Cosine cosineSymbol = new Cosine();
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51 | private static readonly Tangent tanSymbol = new Tangent();
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52 | private static readonly IfThenElse ifThenElseSymbol = new IfThenElse();
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53 | private static readonly And andSymbol = new And();
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54 | private static readonly Or orSymbol = new Or();
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55 | private static readonly Not notSymbol = new Not();
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56 | private static readonly GreaterThan gtSymbol = new GreaterThan();
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57 | private static readonly LessThan ltSymbol = new LessThan();
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58 | private static readonly Integral integralSymbol = new Integral();
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59 | private static readonly LaggedVariable laggedVariableSymbol = new LaggedVariable();
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60 | private static readonly TimeLag timeLagSymbol = new TimeLag();
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61 | private static readonly Sum sumSymbol = new Sum();
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62 | private static readonly Mean meanSymbol = new Mean();
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63 | private static readonly Length lengthSymbol = new Length();
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64 | private static readonly StandardDeviation standardDeviationSymbol = new StandardDeviation();
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65 | private static readonly Variance varianceSymbol = new Variance();
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66 |
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67 | private readonly SymbolicDataAnalysisExpressionTreeVectorInterpreter interpreter;
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68 | private readonly IDataAnalysisProblemData problemData;
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69 |
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70 | public VectorTreeSimplifier(SymbolicDataAnalysisExpressionTreeVectorInterpreter interpreter, IDataAnalysisProblemData problemData) {
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71 | this.interpreter = interpreter;
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72 | this.problemData = problemData;
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73 | }
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74 |
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75 | public ISymbolicExpressionTree Simplify(ISymbolicExpressionTree originalTree) {
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76 | var clone = (ISymbolicExpressionTreeNode)originalTree.Root.Clone();
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77 | // macro expand (initially no argument trees)
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78 | var macroExpandedTree = MacroExpand(clone, clone.GetSubtree(0), new List<ISymbolicExpressionTreeNode>());
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79 | ISymbolicExpressionTreeNode rootNode = (new ProgramRootSymbol()).CreateTreeNode();
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80 | rootNode.AddSubtree(GetSimplifiedTree(macroExpandedTree));
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81 |
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82 | #if DEBUG
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83 | // check that each node is only referenced once
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84 | var nodes = rootNode.IterateNodesPrefix().ToArray();
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85 | foreach (var n in nodes) if (nodes.Count(ni => ni == n) > 1) throw new InvalidOperationException();
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86 | #endif
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87 | return new SymbolicExpressionTree(rootNode);
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88 | }
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89 |
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90 | // the argumentTrees list contains already expanded trees used as arguments for invocations
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91 | private static ISymbolicExpressionTreeNode MacroExpand(ISymbolicExpressionTreeNode root, ISymbolicExpressionTreeNode node,
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92 | IList<ISymbolicExpressionTreeNode> argumentTrees) {
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93 | List<ISymbolicExpressionTreeNode> subtrees = new List<ISymbolicExpressionTreeNode>(node.Subtrees);
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94 | while (node.SubtreeCount > 0) node.RemoveSubtree(0);
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95 | if (node.Symbol is InvokeFunction) {
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96 | var invokeSym = node.Symbol as InvokeFunction;
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97 | var defunNode = FindFunctionDefinition(root, invokeSym.FunctionName);
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98 | var macroExpandedArguments = new List<ISymbolicExpressionTreeNode>();
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99 | foreach (var subtree in subtrees) {
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100 | macroExpandedArguments.Add(MacroExpand(root, subtree, argumentTrees));
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101 | }
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102 | return MacroExpand(root, defunNode, macroExpandedArguments);
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103 | } else if (node.Symbol is Argument) {
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104 | var argSym = node.Symbol as Argument;
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105 | // return the correct argument sub-tree (already macro-expanded)
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106 | return (SymbolicExpressionTreeNode)argumentTrees[argSym.ArgumentIndex].Clone();
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107 | } else {
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108 | // recursive application
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109 | foreach (var subtree in subtrees) {
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110 | node.AddSubtree(MacroExpand(root, subtree, argumentTrees));
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111 | }
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112 | return node;
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113 | }
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114 | }
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115 |
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116 | private static ISymbolicExpressionTreeNode FindFunctionDefinition(ISymbolicExpressionTreeNode root, string functionName) {
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117 | foreach (var subtree in root.Subtrees.OfType<DefunTreeNode>()) {
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118 | if (subtree.FunctionName == functionName) return subtree.GetSubtree(0);
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119 | }
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120 |
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121 | throw new ArgumentException("Definition of function " + functionName + " not found.");
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122 | }
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123 |
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124 | #region symbol predicates
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125 |
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126 | // arithmetic
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127 | private static bool IsDivision(ISymbolicExpressionTreeNode node) {
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128 | return node.Symbol is Division;
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129 | }
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130 |
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131 | private static bool IsMultiplication(ISymbolicExpressionTreeNode node) {
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132 | return node.Symbol is Multiplication;
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133 | }
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134 |
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135 | private static bool IsSubtraction(ISymbolicExpressionTreeNode node) {
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136 | return node.Symbol is Subtraction;
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137 | }
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138 |
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139 | private static bool IsAddition(ISymbolicExpressionTreeNode node) {
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140 | return node.Symbol is Addition;
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141 | }
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142 |
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143 | private static bool IsAverage(ISymbolicExpressionTreeNode node) {
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144 | return node.Symbol is Average;
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145 | }
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146 |
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147 | private static bool IsAbsolute(ISymbolicExpressionTreeNode node) {
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148 | return node.Symbol is Absolute;
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149 | }
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150 |
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151 | // exponential
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152 | private static bool IsLog(ISymbolicExpressionTreeNode node) {
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153 | return node.Symbol is Logarithm;
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154 | }
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155 |
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156 | private static bool IsExp(ISymbolicExpressionTreeNode node) {
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157 | return node.Symbol is Exponential;
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158 | }
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159 |
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160 | private static bool IsRoot(ISymbolicExpressionTreeNode node) {
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161 | return node.Symbol is Root;
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162 | }
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163 |
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164 | private static bool IsSquare(ISymbolicExpressionTreeNode node) {
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165 | return node.Symbol is Square;
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166 | }
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167 |
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168 | private static bool IsSquareRoot(ISymbolicExpressionTreeNode node) {
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169 | return node.Symbol is SquareRoot;
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170 | }
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171 |
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172 | private static bool IsCube(ISymbolicExpressionTreeNode node) {
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173 | return node.Symbol is Cube;
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174 | }
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175 |
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176 | private static bool IsCubeRoot(ISymbolicExpressionTreeNode node) {
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177 | return node.Symbol is CubeRoot;
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178 | }
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179 |
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180 | private static bool IsPower(ISymbolicExpressionTreeNode node) {
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181 | return node.Symbol is Power;
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182 | }
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183 |
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184 | // trigonometric
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185 | private static bool IsSine(ISymbolicExpressionTreeNode node) {
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186 | return node.Symbol is Sine;
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187 | }
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188 |
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189 | private static bool IsCosine(ISymbolicExpressionTreeNode node) {
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190 | return node.Symbol is Cosine;
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191 | }
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192 |
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193 | private static bool IsTangent(ISymbolicExpressionTreeNode node) {
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194 | return node.Symbol is Tangent;
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195 | }
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196 |
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197 | private static bool IsAnalyticalQuotient(ISymbolicExpressionTreeNode node) {
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198 | return node.Symbol is AnalyticQuotient;
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199 | }
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200 |
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201 | // boolean
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202 | private static bool IsIfThenElse(ISymbolicExpressionTreeNode node) {
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203 | return node.Symbol is IfThenElse;
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204 | }
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205 |
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206 | private static bool IsAnd(ISymbolicExpressionTreeNode node) {
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207 | return node.Symbol is And;
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208 | }
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209 |
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210 | private static bool IsOr(ISymbolicExpressionTreeNode node) {
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211 | return node.Symbol is Or;
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212 | }
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213 |
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214 | private static bool IsNot(ISymbolicExpressionTreeNode node) {
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215 | return node.Symbol is Not;
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216 | }
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217 |
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218 | // comparison
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219 | private static bool IsGreaterThan(ISymbolicExpressionTreeNode node) {
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220 | return node.Symbol is GreaterThan;
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221 | }
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222 |
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223 | private static bool IsLessThan(ISymbolicExpressionTreeNode node) {
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224 | return node.Symbol is LessThan;
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225 | }
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226 |
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227 | private static bool IsBoolean(ISymbolicExpressionTreeNode node) {
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228 | return
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229 | node.Symbol is GreaterThan ||
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230 | node.Symbol is LessThan ||
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231 | node.Symbol is And ||
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232 | node.Symbol is Or;
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233 | }
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234 |
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235 | // terminals
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236 | private static bool IsVariable(ISymbolicExpressionTreeNode node) {
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237 | return node.Symbol is Variable;
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238 | }
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239 |
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240 | private static bool IsVariableBase(ISymbolicExpressionTreeNode node) {
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241 | return node is VariableTreeNodeBase;
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242 | }
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243 |
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244 | private static bool IsFactor(ISymbolicExpressionTreeNode node) {
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245 | return node is FactorVariableTreeNode;
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246 | }
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247 |
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248 | private static bool IsBinFactor(ISymbolicExpressionTreeNode node) {
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249 | return node is BinaryFactorVariableTreeNode;
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250 | }
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251 |
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252 | private static bool IsConstant(ISymbolicExpressionTreeNode node) {
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253 | return node.Symbol is Constant;
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254 | }
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255 |
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256 | // dynamic
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257 | private static bool IsTimeLag(ISymbolicExpressionTreeNode node) {
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258 | return node.Symbol is TimeLag;
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259 | }
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260 |
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261 | private static bool IsIntegral(ISymbolicExpressionTreeNode node) {
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262 | return node.Symbol is Integral;
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263 | }
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264 |
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265 | private static bool IsSum(ISymbolicExpressionTreeNode node) {
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266 | return node.Symbol is Sum;
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267 | }
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268 |
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269 | private static bool IsMean(ISymbolicExpressionTreeNode node) {
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270 | return node.Symbol is Mean;
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271 | }
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272 |
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273 | private static bool IsLength(ISymbolicExpressionTreeNode node) {
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274 | return node.Symbol is Length;
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275 | }
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276 |
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277 | private static bool IsStandardDeviation(ISymbolicExpressionTreeNode node) {
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278 | return node.Symbol is StandardDeviation;
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279 | }
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280 |
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281 | private static bool IsVariance(ISymbolicExpressionTreeNode node) {
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282 | return node.Symbol is Variance;
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283 | }
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284 | #endregion
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285 |
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286 | #region type predicates
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287 | public bool IsScalarNode(ISymbolicExpressionTreeNode node) {
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288 | var results = interpreter.EvaluateNode(node, problemData.Dataset, problemData.TrainingIndices);
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289 | return results.All(r => r.IsScalar);
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290 | }
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291 | public bool IsVectorNode(ISymbolicExpressionTreeNode node) {
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292 | var results = interpreter.EvaluateNode(node, problemData.Dataset, problemData.TrainingIndices);
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293 | return results.All(r => r.IsVector);
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294 | }
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295 | #endregion
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296 |
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297 | /// <summary>
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298 | /// Creates a new simplified tree
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299 | /// </summary>
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300 | /// <param name="original"></param>
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301 | /// <returns></returns>
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302 | public ISymbolicExpressionTreeNode GetSimplifiedTree(ISymbolicExpressionTreeNode original) {
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303 | if (IsConstant(original) || IsVariableBase(original)) {
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304 | return (ISymbolicExpressionTreeNode)original.Clone();
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305 | } else if (IsAbsolute(original)) {
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306 | return SimplifyAbsolute(original);
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307 | } else if (IsAddition(original)) {
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308 | return SimplifyAddition(original);
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309 | } else if (IsSubtraction(original)) {
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310 | return SimplifySubtraction(original);
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311 | } else if (IsMultiplication(original)) {
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312 | return SimplifyMultiplication(original);
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313 | } else if (IsDivision(original)) {
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314 | return SimplifyDivision(original);
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315 | } else if (IsAverage(original)) {
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316 | return SimplifyAverage(original);
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317 | } else if (IsLog(original)) {
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318 | return SimplifyLog(original);
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319 | } else if (IsExp(original)) {
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320 | return SimplifyExp(original);
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321 | } else if (IsSquare(original)) {
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322 | return SimplifySquare(original);
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323 | } else if (IsSquareRoot(original)) {
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324 | return SimplifySquareRoot(original);
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325 | } else if (IsCube(original)) {
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326 | return SimplifyCube(original);
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327 | } else if (IsCubeRoot(original)) {
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328 | return SimplifyCubeRoot(original);
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329 | } else if (IsPower(original)) {
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330 | return SimplifyPower(original);
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331 | } else if (IsRoot(original)) {
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332 | return SimplifyRoot(original);
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333 | } else if (IsSine(original)) {
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334 | return SimplifySine(original);
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335 | } else if (IsCosine(original)) {
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336 | return SimplifyCosine(original);
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337 | } else if (IsTangent(original)) {
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338 | return SimplifyTangent(original);
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339 | } else if (IsAnalyticalQuotient(original)) {
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340 | return SimplifyAnalyticalQuotient(original);
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341 | } else if (IsIfThenElse(original)) {
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342 | return SimplifyIfThenElse(original);
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343 | } else if (IsGreaterThan(original)) {
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344 | return SimplifyGreaterThan(original);
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345 | } else if (IsLessThan(original)) {
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346 | return SimplifyLessThan(original);
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347 | } else if (IsAnd(original)) {
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348 | return SimplifyAnd(original);
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349 | } else if (IsOr(original)) {
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350 | return SimplifyOr(original);
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351 | } else if (IsNot(original)) {
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352 | return SimplifyNot(original);
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353 | } else if (IsTimeLag(original)) {
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354 | return SimplifyTimeLag(original);
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355 | } else if (IsIntegral(original)) {
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356 | return SimplifyIntegral(original);
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357 | } else if (IsSum(original)) {
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358 | return SimplifySumAggregation(original);
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359 | } else if (IsMean(original)) {
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360 | return SimplifyMeanAggregation(original);
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361 | } else if (IsLength(original)) {
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362 | return SimplifyLengthAggregation(original);
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363 | } else if (IsStandardDeviation(original)) {
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364 | return SimplifyStandardDeviationAggregation(original);
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365 | } else if (IsVariance(original)) {
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366 | return SimplifyVarianceAggregation(original);
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367 | } else {
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368 | return SimplifyAny(original);
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369 | }
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370 | }
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371 |
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372 | #region specific simplification routines
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373 |
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374 | private ISymbolicExpressionTreeNode SimplifyAny(ISymbolicExpressionTreeNode original) {
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375 | // can't simplify this function but simplify all subtrees
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376 | List<ISymbolicExpressionTreeNode> subtrees = new List<ISymbolicExpressionTreeNode>(original.Subtrees);
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377 | while (original.Subtrees.Count() > 0) original.RemoveSubtree(0);
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378 | var clone = (SymbolicExpressionTreeNode)original.Clone();
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379 | List<ISymbolicExpressionTreeNode> simplifiedSubtrees = new List<ISymbolicExpressionTreeNode>();
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380 | foreach (var subtree in subtrees) {
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381 | simplifiedSubtrees.Add(GetSimplifiedTree(subtree));
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382 | original.AddSubtree(subtree);
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383 | }
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384 | foreach (var simplifiedSubtree in simplifiedSubtrees) {
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385 | clone.AddSubtree(simplifiedSubtree);
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386 | }
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387 | if (simplifiedSubtrees.TrueForAll(t => IsConstant(t))) {
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388 | SimplifyConstantExpression(clone);
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389 | }
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390 | return clone;
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391 | }
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392 |
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393 | private ISymbolicExpressionTreeNode SimplifyConstantExpression(ISymbolicExpressionTreeNode original) {
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394 | // not yet implemented
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395 | return original;
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396 | }
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397 |
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398 | private ISymbolicExpressionTreeNode SimplifyAverage(ISymbolicExpressionTreeNode original) {
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399 | if (original.Subtrees.Count() == 1) {
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400 | return GetSimplifiedTree(original.GetSubtree(0));
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401 | } else {
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402 | // simplify expressions x0..xn
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403 | // make sum(x0..xn) / n
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404 | var sum = original.Subtrees
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405 | .Select(GetSimplifiedTree)
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406 | .Aggregate(MakeSum);
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407 | return MakeFraction(sum, MakeConstant(original.Subtrees.Count()));
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408 | }
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409 | }
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410 |
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411 | private ISymbolicExpressionTreeNode SimplifyDivision(ISymbolicExpressionTreeNode original) {
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412 | if (original.Subtrees.Count() == 1) {
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413 | return Invert(GetSimplifiedTree(original.GetSubtree(0)));
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414 | } else {
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415 | // simplify expressions x0..xn
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416 | // make multiplication (x0 * 1/(x1 * x1 * .. * xn))
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417 | var first = original.GetSubtree(0);
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418 | var second = original.GetSubtree(1);
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419 | var remaining = original.Subtrees.Skip(2);
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420 | return
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421 | MakeProduct(GetSimplifiedTree(first),
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422 | Invert(remaining.Aggregate(GetSimplifiedTree(second), (a, b) => MakeProduct(a, GetSimplifiedTree(b)))));
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423 | }
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424 | }
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425 |
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426 | private ISymbolicExpressionTreeNode SimplifyMultiplication(ISymbolicExpressionTreeNode original) {
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427 | if (original.Subtrees.Count() == 1) {
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428 | return GetSimplifiedTree(original.GetSubtree(0));
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429 | } else {
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430 | return original.Subtrees
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431 | .Select(GetSimplifiedTree)
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432 | .Aggregate(MakeProduct);
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433 | }
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434 | }
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435 |
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436 | private ISymbolicExpressionTreeNode SimplifySubtraction(ISymbolicExpressionTreeNode original) {
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437 | if (original.Subtrees.Count() == 1) {
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438 | return Negate(GetSimplifiedTree(original.GetSubtree(0)));
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439 | } else {
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440 | // simplify expressions x0..xn
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441 | // make addition (x0,-x1..-xn)
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442 | var first = original.Subtrees.First();
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443 | var remaining = original.Subtrees.Skip(1);
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444 | return remaining.Aggregate(GetSimplifiedTree(first), (a, b) => MakeSum(a, Negate(GetSimplifiedTree(b))));
|
---|
445 | }
|
---|
446 | }
|
---|
447 |
|
---|
448 | private ISymbolicExpressionTreeNode SimplifyAddition(ISymbolicExpressionTreeNode original) {
|
---|
449 | if (original.Subtrees.Count() == 1) {
|
---|
450 | return GetSimplifiedTree(original.GetSubtree(0));
|
---|
451 | } else {
|
---|
452 | // simplify expression x0..xn
|
---|
453 | // make addition (x0..xn)
|
---|
454 | return original.Subtrees
|
---|
455 | .Select(GetSimplifiedTree)
|
---|
456 | .Aggregate(MakeSum);
|
---|
457 | }
|
---|
458 | }
|
---|
459 |
|
---|
460 | private ISymbolicExpressionTreeNode SimplifyAbsolute(ISymbolicExpressionTreeNode original) {
|
---|
461 | return MakeAbs(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
462 | }
|
---|
463 |
|
---|
464 | private ISymbolicExpressionTreeNode SimplifyNot(ISymbolicExpressionTreeNode original) {
|
---|
465 | return MakeNot(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
466 | }
|
---|
467 |
|
---|
468 | private ISymbolicExpressionTreeNode SimplifyOr(ISymbolicExpressionTreeNode original) {
|
---|
469 | return original.Subtrees
|
---|
470 | .Select(GetSimplifiedTree)
|
---|
471 | .Aggregate(MakeOr);
|
---|
472 | }
|
---|
473 |
|
---|
474 | private ISymbolicExpressionTreeNode SimplifyAnd(ISymbolicExpressionTreeNode original) {
|
---|
475 | return original.Subtrees
|
---|
476 | .Select(GetSimplifiedTree)
|
---|
477 | .Aggregate(MakeAnd);
|
---|
478 | }
|
---|
479 |
|
---|
480 | private ISymbolicExpressionTreeNode SimplifyLessThan(ISymbolicExpressionTreeNode original) {
|
---|
481 | return MakeLessThan(GetSimplifiedTree(original.GetSubtree(0)), GetSimplifiedTree(original.GetSubtree(1)));
|
---|
482 | }
|
---|
483 |
|
---|
484 | private ISymbolicExpressionTreeNode SimplifyGreaterThan(ISymbolicExpressionTreeNode original) {
|
---|
485 | return MakeGreaterThan(GetSimplifiedTree(original.GetSubtree(0)), GetSimplifiedTree(original.GetSubtree(1)));
|
---|
486 | }
|
---|
487 |
|
---|
488 | private ISymbolicExpressionTreeNode SimplifyIfThenElse(ISymbolicExpressionTreeNode original) {
|
---|
489 | return MakeIfThenElse(GetSimplifiedTree(original.GetSubtree(0)), GetSimplifiedTree(original.GetSubtree(1)),
|
---|
490 | GetSimplifiedTree(original.GetSubtree(2)));
|
---|
491 | }
|
---|
492 |
|
---|
493 | private ISymbolicExpressionTreeNode SimplifyTangent(ISymbolicExpressionTreeNode original) {
|
---|
494 | return MakeTangent(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
495 | }
|
---|
496 |
|
---|
497 | private ISymbolicExpressionTreeNode SimplifyCosine(ISymbolicExpressionTreeNode original) {
|
---|
498 | return MakeCosine(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
499 | }
|
---|
500 |
|
---|
501 | private ISymbolicExpressionTreeNode SimplifySine(ISymbolicExpressionTreeNode original) {
|
---|
502 | return MakeSine(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
503 | }
|
---|
504 |
|
---|
505 | private ISymbolicExpressionTreeNode SimplifyExp(ISymbolicExpressionTreeNode original) {
|
---|
506 | return MakeExp(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
507 | }
|
---|
508 |
|
---|
509 | private ISymbolicExpressionTreeNode SimplifySquare(ISymbolicExpressionTreeNode original) {
|
---|
510 | return MakeSquare(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
511 | }
|
---|
512 |
|
---|
513 | private ISymbolicExpressionTreeNode SimplifySquareRoot(ISymbolicExpressionTreeNode original) {
|
---|
514 | return MakeSquareRoot(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
515 | }
|
---|
516 | private ISymbolicExpressionTreeNode SimplifyCube(ISymbolicExpressionTreeNode original) {
|
---|
517 | return MakeCube(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
518 | }
|
---|
519 |
|
---|
520 | private ISymbolicExpressionTreeNode SimplifyCubeRoot(ISymbolicExpressionTreeNode original) {
|
---|
521 | return MakeCubeRoot(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
522 | }
|
---|
523 |
|
---|
524 | private ISymbolicExpressionTreeNode SimplifyLog(ISymbolicExpressionTreeNode original) {
|
---|
525 | return MakeLog(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
526 | }
|
---|
527 |
|
---|
528 | private ISymbolicExpressionTreeNode SimplifyRoot(ISymbolicExpressionTreeNode original) {
|
---|
529 | return MakeRoot(GetSimplifiedTree(original.GetSubtree(0)), GetSimplifiedTree(original.GetSubtree(1)));
|
---|
530 | }
|
---|
531 |
|
---|
532 | private ISymbolicExpressionTreeNode SimplifyPower(ISymbolicExpressionTreeNode original) {
|
---|
533 | return MakePower(GetSimplifiedTree(original.GetSubtree(0)), GetSimplifiedTree(original.GetSubtree(1)));
|
---|
534 | }
|
---|
535 |
|
---|
536 | private ISymbolicExpressionTreeNode SimplifyAnalyticalQuotient(ISymbolicExpressionTreeNode original) {
|
---|
537 | return MakeAnalyticalQuotient(GetSimplifiedTree(original.GetSubtree(0)), GetSimplifiedTree(original.GetSubtree(1)));
|
---|
538 | }
|
---|
539 |
|
---|
540 | private ISymbolicExpressionTreeNode SimplifyTimeLag(ISymbolicExpressionTreeNode original) {
|
---|
541 | var laggedTreeNode = original as ILaggedTreeNode;
|
---|
542 | var simplifiedSubtree = GetSimplifiedTree(original.GetSubtree(0));
|
---|
543 | if (!ContainsVariableCondition(simplifiedSubtree)) {
|
---|
544 | return AddLagToDynamicNodes(simplifiedSubtree, laggedTreeNode.Lag);
|
---|
545 | } else {
|
---|
546 | return MakeTimeLag(simplifiedSubtree, laggedTreeNode.Lag);
|
---|
547 | }
|
---|
548 | }
|
---|
549 |
|
---|
550 | private ISymbolicExpressionTreeNode SimplifyIntegral(ISymbolicExpressionTreeNode original) {
|
---|
551 | var laggedTreeNode = original as ILaggedTreeNode;
|
---|
552 | var simplifiedSubtree = GetSimplifiedTree(original.GetSubtree(0));
|
---|
553 | if (IsConstant(simplifiedSubtree)) {
|
---|
554 | return GetSimplifiedTree(MakeProduct(simplifiedSubtree, MakeConstant(-laggedTreeNode.Lag)));
|
---|
555 | } else {
|
---|
556 | return MakeIntegral(simplifiedSubtree, laggedTreeNode.Lag);
|
---|
557 | }
|
---|
558 | }
|
---|
559 |
|
---|
560 | private ISymbolicExpressionTreeNode SimplifySumAggregation(ISymbolicExpressionTreeNode original) {
|
---|
561 | return MakeSumAggregation(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
562 | }
|
---|
563 |
|
---|
564 | private ISymbolicExpressionTreeNode SimplifyMeanAggregation(ISymbolicExpressionTreeNode original) {
|
---|
565 | return MakeMeanAggregation(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
566 | }
|
---|
567 |
|
---|
568 | private ISymbolicExpressionTreeNode SimplifyLengthAggregation(ISymbolicExpressionTreeNode original) {
|
---|
569 | return MakeLengthAggregation(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
570 | }
|
---|
571 |
|
---|
572 | private ISymbolicExpressionTreeNode SimplifyStandardDeviationAggregation(ISymbolicExpressionTreeNode original) {
|
---|
573 | return MakeStandardDeviationAggregation(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
574 | }
|
---|
575 |
|
---|
576 | private ISymbolicExpressionTreeNode SimplifyVarianceAggregation(ISymbolicExpressionTreeNode original) {
|
---|
577 | return MakeVarianceAggregation(GetSimplifiedTree(original.GetSubtree(0)));
|
---|
578 | }
|
---|
579 | #endregion
|
---|
580 |
|
---|
581 | #region low level tree restructuring
|
---|
582 |
|
---|
583 | private ISymbolicExpressionTreeNode MakeTimeLag(ISymbolicExpressionTreeNode subtree, int lag) {
|
---|
584 | if (lag == 0) return subtree;
|
---|
585 | if (IsConstant(subtree)) return subtree;
|
---|
586 | var lagNode = (LaggedTreeNode)timeLagSymbol.CreateTreeNode();
|
---|
587 | lagNode.Lag = lag;
|
---|
588 | lagNode.AddSubtree(subtree);
|
---|
589 | return lagNode;
|
---|
590 | }
|
---|
591 |
|
---|
592 | private ISymbolicExpressionTreeNode MakeIntegral(ISymbolicExpressionTreeNode subtree, int lag) {
|
---|
593 | if (lag == 0) return subtree;
|
---|
594 | else if (lag == -1 || lag == 1) {
|
---|
595 | return MakeSum(subtree, AddLagToDynamicNodes((ISymbolicExpressionTreeNode)subtree.Clone(), lag));
|
---|
596 | } else {
|
---|
597 | var node = (LaggedTreeNode)integralSymbol.CreateTreeNode();
|
---|
598 | node.Lag = lag;
|
---|
599 | node.AddSubtree(subtree);
|
---|
600 | return node;
|
---|
601 | }
|
---|
602 | }
|
---|
603 |
|
---|
604 | private ISymbolicExpressionTreeNode MakeNot(ISymbolicExpressionTreeNode t) {
|
---|
605 | if (IsConstant(t)) {
|
---|
606 | var constNode = t as ConstantTreeNode;
|
---|
607 | if (constNode.Value > 0) return MakeConstant(-1.0);
|
---|
608 | else return MakeConstant(1.0);
|
---|
609 | } else if (IsNot(t)) {
|
---|
610 | return t.GetSubtree(0);
|
---|
611 | } else if (!IsBoolean(t)) {
|
---|
612 | var gtNode = gtSymbol.CreateTreeNode();
|
---|
613 | gtNode.AddSubtree(t);
|
---|
614 | gtNode.AddSubtree(MakeConstant(0.0));
|
---|
615 | var notNode = notSymbol.CreateTreeNode();
|
---|
616 | notNode.AddSubtree(gtNode);
|
---|
617 | return notNode;
|
---|
618 | } else {
|
---|
619 | var notNode = notSymbol.CreateTreeNode();
|
---|
620 | notNode.AddSubtree(t);
|
---|
621 | return notNode;
|
---|
622 | }
|
---|
623 | }
|
---|
624 |
|
---|
625 | private ISymbolicExpressionTreeNode MakeOr(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
|
---|
626 | if (IsConstant(a) && IsConstant(b)) {
|
---|
627 | var constA = a as ConstantTreeNode;
|
---|
628 | var constB = b as ConstantTreeNode;
|
---|
629 | if (constA.Value > 0.0 || constB.Value > 0.0) {
|
---|
630 | return MakeConstant(1.0);
|
---|
631 | } else {
|
---|
632 | return MakeConstant(-1.0);
|
---|
633 | }
|
---|
634 | } else if (IsConstant(a)) {
|
---|
635 | return MakeOr(b, a);
|
---|
636 | } else if (IsConstant(b)) {
|
---|
637 | var constT = b as ConstantTreeNode;
|
---|
638 | if (constT.Value > 0.0) {
|
---|
639 | // boolean expression is necessarily true
|
---|
640 | return MakeConstant(1.0);
|
---|
641 | } else {
|
---|
642 | // the constant value has no effect on the result of the boolean condition so we can drop the constant term
|
---|
643 | var orNode = orSymbol.CreateTreeNode();
|
---|
644 | orNode.AddSubtree(a);
|
---|
645 | return orNode;
|
---|
646 | }
|
---|
647 | } else {
|
---|
648 | var orNode = orSymbol.CreateTreeNode();
|
---|
649 | orNode.AddSubtree(a);
|
---|
650 | orNode.AddSubtree(b);
|
---|
651 | return orNode;
|
---|
652 | }
|
---|
653 | }
|
---|
654 |
|
---|
655 | private ISymbolicExpressionTreeNode MakeAnd(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
|
---|
656 | if (IsConstant(a) && IsConstant(b)) {
|
---|
657 | var constA = a as ConstantTreeNode;
|
---|
658 | var constB = b as ConstantTreeNode;
|
---|
659 | if (constA.Value > 0.0 && constB.Value > 0.0) {
|
---|
660 | return MakeConstant(1.0);
|
---|
661 | } else {
|
---|
662 | return MakeConstant(-1.0);
|
---|
663 | }
|
---|
664 | } else if (IsConstant(a)) {
|
---|
665 | return MakeAnd(b, a);
|
---|
666 | } else if (IsConstant(b)) {
|
---|
667 | var constB = b as ConstantTreeNode;
|
---|
668 | if (constB.Value > 0.0) {
|
---|
669 | // the constant value has no effect on the result of the boolean condition so we can drop the constant term
|
---|
670 | var andNode = andSymbol.CreateTreeNode();
|
---|
671 | andNode.AddSubtree(a);
|
---|
672 | return andNode;
|
---|
673 | } else {
|
---|
674 | // boolean expression is necessarily false
|
---|
675 | return MakeConstant(-1.0);
|
---|
676 | }
|
---|
677 | } else {
|
---|
678 | var andNode = andSymbol.CreateTreeNode();
|
---|
679 | andNode.AddSubtree(a);
|
---|
680 | andNode.AddSubtree(b);
|
---|
681 | return andNode;
|
---|
682 | }
|
---|
683 | }
|
---|
684 |
|
---|
685 | private ISymbolicExpressionTreeNode MakeLessThan(ISymbolicExpressionTreeNode leftSide,
|
---|
686 | ISymbolicExpressionTreeNode rightSide) {
|
---|
687 | if (IsConstant(leftSide) && IsConstant(rightSide)) {
|
---|
688 | var lsConst = leftSide as ConstantTreeNode;
|
---|
689 | var rsConst = rightSide as ConstantTreeNode;
|
---|
690 | if (lsConst.Value < rsConst.Value) return MakeConstant(1.0);
|
---|
691 | else return MakeConstant(-1.0);
|
---|
692 | } else {
|
---|
693 | var ltNode = ltSymbol.CreateTreeNode();
|
---|
694 | ltNode.AddSubtree(leftSide);
|
---|
695 | ltNode.AddSubtree(rightSide);
|
---|
696 | return ltNode;
|
---|
697 | }
|
---|
698 | }
|
---|
699 |
|
---|
700 | private ISymbolicExpressionTreeNode MakeGreaterThan(ISymbolicExpressionTreeNode leftSide,
|
---|
701 | ISymbolicExpressionTreeNode rightSide) {
|
---|
702 | if (IsConstant(leftSide) && IsConstant(rightSide)) {
|
---|
703 | var lsConst = leftSide as ConstantTreeNode;
|
---|
704 | var rsConst = rightSide as ConstantTreeNode;
|
---|
705 | if (lsConst.Value > rsConst.Value) return MakeConstant(1.0);
|
---|
706 | else return MakeConstant(-1.0);
|
---|
707 | } else {
|
---|
708 | var gtNode = gtSymbol.CreateTreeNode();
|
---|
709 | gtNode.AddSubtree(leftSide);
|
---|
710 | gtNode.AddSubtree(rightSide);
|
---|
711 | return gtNode;
|
---|
712 | }
|
---|
713 | }
|
---|
714 |
|
---|
715 | private ISymbolicExpressionTreeNode MakeIfThenElse(ISymbolicExpressionTreeNode condition,
|
---|
716 | ISymbolicExpressionTreeNode trueBranch, ISymbolicExpressionTreeNode falseBranch) {
|
---|
717 | if (IsConstant(condition)) {
|
---|
718 | var constT = condition as ConstantTreeNode;
|
---|
719 | if (constT.Value > 0.0) return trueBranch;
|
---|
720 | else return falseBranch;
|
---|
721 | } else {
|
---|
722 | var ifNode = ifThenElseSymbol.CreateTreeNode();
|
---|
723 | if (IsBoolean(condition)) {
|
---|
724 | ifNode.AddSubtree(condition);
|
---|
725 | } else {
|
---|
726 | var gtNode = gtSymbol.CreateTreeNode();
|
---|
727 | gtNode.AddSubtree(condition);
|
---|
728 | gtNode.AddSubtree(MakeConstant(0.0));
|
---|
729 | ifNode.AddSubtree(gtNode);
|
---|
730 | }
|
---|
731 | ifNode.AddSubtree(trueBranch);
|
---|
732 | ifNode.AddSubtree(falseBranch);
|
---|
733 | return ifNode;
|
---|
734 | }
|
---|
735 | }
|
---|
736 |
|
---|
737 | private ISymbolicExpressionTreeNode MakeSine(ISymbolicExpressionTreeNode node) {
|
---|
738 | if (IsConstant(node)) {
|
---|
739 | var constT = node as ConstantTreeNode;
|
---|
740 | return MakeConstant(Math.Sin(constT.Value));
|
---|
741 | } else if (IsFactor(node)) {
|
---|
742 | var factor = node as FactorVariableTreeNode;
|
---|
743 | return MakeFactor(factor.Symbol, factor.VariableName, factor.Weights.Select(Math.Sin));
|
---|
744 | } else if (IsBinFactor(node)) {
|
---|
745 | var binFactor = node as BinaryFactorVariableTreeNode;
|
---|
746 | return MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, Math.Sin(binFactor.Weight));
|
---|
747 | } else {
|
---|
748 | var sineNode = sineSymbol.CreateTreeNode();
|
---|
749 | sineNode.AddSubtree(node);
|
---|
750 | return sineNode;
|
---|
751 | }
|
---|
752 | }
|
---|
753 |
|
---|
754 | private ISymbolicExpressionTreeNode MakeTangent(ISymbolicExpressionTreeNode node) {
|
---|
755 | if (IsConstant(node)) {
|
---|
756 | var constT = node as ConstantTreeNode;
|
---|
757 | return MakeConstant(Math.Tan(constT.Value));
|
---|
758 | } else if (IsFactor(node)) {
|
---|
759 | var factor = node as FactorVariableTreeNode;
|
---|
760 | return MakeFactor(factor.Symbol, factor.VariableName, factor.Weights.Select(Math.Tan));
|
---|
761 | } else if (IsBinFactor(node)) {
|
---|
762 | var binFactor = node as BinaryFactorVariableTreeNode;
|
---|
763 | return MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, Math.Tan(binFactor.Weight));
|
---|
764 | } else {
|
---|
765 | var tanNode = tanSymbol.CreateTreeNode();
|
---|
766 | tanNode.AddSubtree(node);
|
---|
767 | return tanNode;
|
---|
768 | }
|
---|
769 | }
|
---|
770 |
|
---|
771 | private ISymbolicExpressionTreeNode MakeCosine(ISymbolicExpressionTreeNode node) {
|
---|
772 | if (IsConstant(node)) {
|
---|
773 | var constT = node as ConstantTreeNode;
|
---|
774 | return MakeConstant(Math.Cos(constT.Value));
|
---|
775 | } else if (IsFactor(node)) {
|
---|
776 | var factor = node as FactorVariableTreeNode;
|
---|
777 | return MakeFactor(factor.Symbol, factor.VariableName, factor.Weights.Select(Math.Cos));
|
---|
778 | } else if (IsBinFactor(node)) {
|
---|
779 | var binFactor = node as BinaryFactorVariableTreeNode;
|
---|
780 | // cos(0) = 1 see similar case for Exp(binfactor)
|
---|
781 | return MakeSum(MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, Math.Cos(binFactor.Weight) - 1),
|
---|
782 | MakeConstant(1.0));
|
---|
783 | } else {
|
---|
784 | var cosNode = cosineSymbol.CreateTreeNode();
|
---|
785 | cosNode.AddSubtree(node);
|
---|
786 | return cosNode;
|
---|
787 | }
|
---|
788 | }
|
---|
789 |
|
---|
790 | private ISymbolicExpressionTreeNode MakeExp(ISymbolicExpressionTreeNode node) {
|
---|
791 | if (IsConstant(node)) {
|
---|
792 | var constT = node as ConstantTreeNode;
|
---|
793 | return MakeConstant(Math.Exp(constT.Value));
|
---|
794 | } else if (IsFactor(node)) {
|
---|
795 | var factNode = node as FactorVariableTreeNode;
|
---|
796 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => Math.Exp(w)));
|
---|
797 | } else if (IsBinFactor(node)) {
|
---|
798 | // exp( binfactor w val=a) = if(val=a) exp(w) else exp(0) = binfactor( (exp(w) - 1) val a) + 1
|
---|
799 | var binFactor = node as BinaryFactorVariableTreeNode;
|
---|
800 | return
|
---|
801 | MakeSum(MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, Math.Exp(binFactor.Weight) - 1), MakeConstant(1.0));
|
---|
802 | } else if (IsLog(node)) {
|
---|
803 | return node.GetSubtree(0);
|
---|
804 | } else if (IsAddition(node)) {
|
---|
805 | return node.Subtrees.Select(s => MakeExp(s)).Aggregate((s, t) => MakeProduct(s, t));
|
---|
806 | } else if (IsSubtraction(node)) {
|
---|
807 | return node.Subtrees.Select(s => MakeExp(s)).Aggregate((s, t) => MakeProduct(s, Negate(t)));
|
---|
808 | } else {
|
---|
809 | var expNode = expSymbol.CreateTreeNode();
|
---|
810 | expNode.AddSubtree(node);
|
---|
811 | return expNode;
|
---|
812 | }
|
---|
813 | }
|
---|
814 | private ISymbolicExpressionTreeNode MakeLog(ISymbolicExpressionTreeNode node) {
|
---|
815 | if (IsConstant(node)) {
|
---|
816 | var constT = node as ConstantTreeNode;
|
---|
817 | return MakeConstant(Math.Log(constT.Value));
|
---|
818 | } else if (IsFactor(node)) {
|
---|
819 | var factNode = node as FactorVariableTreeNode;
|
---|
820 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => Math.Log(w)));
|
---|
821 | } else if (IsExp(node)) {
|
---|
822 | return node.GetSubtree(0);
|
---|
823 | } else if (IsSquareRoot(node)) {
|
---|
824 | return MakeFraction(MakeLog(node.GetSubtree(0)), MakeConstant(2.0));
|
---|
825 | } else {
|
---|
826 | var logNode = logSymbol.CreateTreeNode();
|
---|
827 | logNode.AddSubtree(node);
|
---|
828 | return logNode;
|
---|
829 | }
|
---|
830 | }
|
---|
831 |
|
---|
832 | private ISymbolicExpressionTreeNode MakeSquare(ISymbolicExpressionTreeNode node) {
|
---|
833 | if (IsConstant(node)) {
|
---|
834 | var constT = node as ConstantTreeNode;
|
---|
835 | return MakeConstant(constT.Value * constT.Value);
|
---|
836 | } else if (IsFactor(node)) {
|
---|
837 | var factNode = node as FactorVariableTreeNode;
|
---|
838 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => w * w));
|
---|
839 | } else if (IsBinFactor(node)) {
|
---|
840 | var binFactor = node as BinaryFactorVariableTreeNode;
|
---|
841 | return MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, binFactor.Weight * binFactor.Weight);
|
---|
842 | } else if (IsSquareRoot(node)) {
|
---|
843 | return node.GetSubtree(0);
|
---|
844 | } else if (IsMultiplication(node)) {
|
---|
845 | // sqr( x * y ) = sqr(x) * sqr(y)
|
---|
846 | var mulNode = mulSymbol.CreateTreeNode();
|
---|
847 | foreach (var subtree in node.Subtrees) {
|
---|
848 | mulNode.AddSubtree(MakeSquare(subtree));
|
---|
849 | }
|
---|
850 | return mulNode;
|
---|
851 | } else if (IsAbsolute(node)) {
|
---|
852 | return MakeSquare(node.GetSubtree(0)); // sqr(abs(x)) = sqr(x)
|
---|
853 | } else if (IsExp(node)) {
|
---|
854 | return MakeExp(MakeProduct(node.GetSubtree(0), MakeConstant(2.0))); // sqr(exp(x)) = exp(2x)
|
---|
855 | } else if (IsCube(node)) {
|
---|
856 | return MakePower(node.GetSubtree(0), MakeConstant(6));
|
---|
857 | } else {
|
---|
858 | var sqrNode = sqrSymbol.CreateTreeNode();
|
---|
859 | sqrNode.AddSubtree(node);
|
---|
860 | return sqrNode;
|
---|
861 | }
|
---|
862 | }
|
---|
863 |
|
---|
864 | private ISymbolicExpressionTreeNode MakeCube(ISymbolicExpressionTreeNode node) {
|
---|
865 | if (IsConstant(node)) {
|
---|
866 | var constT = node as ConstantTreeNode;
|
---|
867 | return MakeConstant(constT.Value * constT.Value * constT.Value);
|
---|
868 | } else if (IsFactor(node)) {
|
---|
869 | var factNode = node as FactorVariableTreeNode;
|
---|
870 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => w * w * w));
|
---|
871 | } else if (IsBinFactor(node)) {
|
---|
872 | var binFactor = node as BinaryFactorVariableTreeNode;
|
---|
873 | return MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, binFactor.Weight * binFactor.Weight * binFactor.Weight);
|
---|
874 | } else if (IsCubeRoot(node)) {
|
---|
875 | return node.GetSubtree(0); // NOTE: not really accurate because cuberoot(x) with negative x is evaluated to NaN and after this simplification we evaluate as x
|
---|
876 | } else if (IsExp(node)) {
|
---|
877 | return MakeExp(MakeProduct(node.GetSubtree(0), MakeConstant(3)));
|
---|
878 | } else if (IsSquare(node)) {
|
---|
879 | return MakePower(node.GetSubtree(0), MakeConstant(6));
|
---|
880 | } else {
|
---|
881 | var cubeNode = cubeSymbol.CreateTreeNode();
|
---|
882 | cubeNode.AddSubtree(node);
|
---|
883 | return cubeNode;
|
---|
884 | }
|
---|
885 | }
|
---|
886 |
|
---|
887 | private ISymbolicExpressionTreeNode MakeAbs(ISymbolicExpressionTreeNode node) {
|
---|
888 | if (IsConstant(node)) {
|
---|
889 | var constT = node as ConstantTreeNode;
|
---|
890 | return MakeConstant(Math.Abs(constT.Value));
|
---|
891 | } else if (IsFactor(node)) {
|
---|
892 | var factNode = node as FactorVariableTreeNode;
|
---|
893 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => Math.Abs(w)));
|
---|
894 | } else if (IsBinFactor(node)) {
|
---|
895 | var binFactor = node as BinaryFactorVariableTreeNode;
|
---|
896 | return MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, Math.Abs(binFactor.Weight));
|
---|
897 | } else if (IsSquare(node) || IsExp(node) || IsSquareRoot(node) || IsCubeRoot(node)) {
|
---|
898 | return node; // abs(sqr(x)) = sqr(x), abs(exp(x)) = exp(x) ...
|
---|
899 | } else if (IsMultiplication(node)) {
|
---|
900 | var mul = mulSymbol.CreateTreeNode();
|
---|
901 | foreach (var st in node.Subtrees) {
|
---|
902 | mul.AddSubtree(MakeAbs(st));
|
---|
903 | }
|
---|
904 | return mul;
|
---|
905 | } else if (IsDivision(node)) {
|
---|
906 | var div = divSymbol.CreateTreeNode();
|
---|
907 | foreach (var st in node.Subtrees) {
|
---|
908 | div.AddSubtree(MakeAbs(st));
|
---|
909 | }
|
---|
910 | return div;
|
---|
911 | } else {
|
---|
912 | var absNode = absSymbol.CreateTreeNode();
|
---|
913 | absNode.AddSubtree(node);
|
---|
914 | return absNode;
|
---|
915 | }
|
---|
916 | }
|
---|
917 |
|
---|
918 | // constant folding only
|
---|
919 | private ISymbolicExpressionTreeNode MakeAnalyticalQuotient(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
|
---|
920 | if (IsConstant(b)) {
|
---|
921 | var c = b as ConstantTreeNode;
|
---|
922 | return MakeFraction(a, MakeConstant(Math.Sqrt(1.0 + c.Value * c.Value)));
|
---|
923 | } else if (IsFactor(b)) {
|
---|
924 | var factNode = b as FactorVariableTreeNode;
|
---|
925 | return MakeFraction(a, MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => Math.Sqrt(1.0 + w * w))));
|
---|
926 | } else if (IsBinFactor(b)) {
|
---|
927 | var binFactor = b as BinaryFactorVariableTreeNode;
|
---|
928 | return MakeFraction(a, MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, Math.Sqrt(1.0 + binFactor.Weight * binFactor.Weight)));
|
---|
929 | } else {
|
---|
930 | var aqNode = aqSymbol.CreateTreeNode();
|
---|
931 | aqNode.AddSubtree(a);
|
---|
932 | aqNode.AddSubtree(b);
|
---|
933 | return aqNode;
|
---|
934 | }
|
---|
935 | }
|
---|
936 |
|
---|
937 | private ISymbolicExpressionTreeNode MakeSquareRoot(ISymbolicExpressionTreeNode node) {
|
---|
938 | if (IsConstant(node)) {
|
---|
939 | var constT = node as ConstantTreeNode;
|
---|
940 | return MakeConstant(Math.Sqrt(constT.Value));
|
---|
941 | } else if (IsFactor(node)) {
|
---|
942 | var factNode = node as FactorVariableTreeNode;
|
---|
943 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => Math.Sqrt(w)));
|
---|
944 | } else if (IsBinFactor(node)) {
|
---|
945 | var binFactor = node as BinaryFactorVariableTreeNode;
|
---|
946 | return MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, Math.Sqrt(binFactor.Weight));
|
---|
947 | } else if (IsSquare(node)) {
|
---|
948 | return node.GetSubtree(0); // NOTE: not really accurate because sqrt(x) with negative x is evaluated to NaN and after this simplification we evaluate as x
|
---|
949 | } else {
|
---|
950 | var sqrtNode = sqrtSymbol.CreateTreeNode();
|
---|
951 | sqrtNode.AddSubtree(node);
|
---|
952 | return sqrtNode;
|
---|
953 | }
|
---|
954 | }
|
---|
955 |
|
---|
956 | private ISymbolicExpressionTreeNode MakeCubeRoot(ISymbolicExpressionTreeNode node) {
|
---|
957 | if (IsConstant(node)) {
|
---|
958 | var constT = node as ConstantTreeNode;
|
---|
959 | return MakeConstant(Math.Pow(constT.Value, 1.0 / 3.0));
|
---|
960 | } else if (IsFactor(node)) {
|
---|
961 | var factNode = node as FactorVariableTreeNode;
|
---|
962 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => Math.Pow(w, 1.0 / 3.0)));
|
---|
963 | } else if (IsBinFactor(node)) {
|
---|
964 | var binFactor = node as BinaryFactorVariableTreeNode;
|
---|
965 | return MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, Math.Sqrt(Math.Pow(binFactor.Weight, 1.0 / 3.0)));
|
---|
966 | } else if (IsCube(node)) {
|
---|
967 | return node.GetSubtree(0);
|
---|
968 | } else {
|
---|
969 | var cubeRootNode = cubeRootSymbol.CreateTreeNode();
|
---|
970 | cubeRootNode.AddSubtree(node);
|
---|
971 | return cubeRootNode;
|
---|
972 | }
|
---|
973 | }
|
---|
974 |
|
---|
975 | private ISymbolicExpressionTreeNode MakeRoot(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
|
---|
976 | if (IsConstant(a) && IsConstant(b)) {
|
---|
977 | var constA = a as ConstantTreeNode;
|
---|
978 | var constB = b as ConstantTreeNode;
|
---|
979 | return MakeConstant(Math.Pow(constA.Value, 1.0 / Math.Round(constB.Value)));
|
---|
980 | } else if (IsFactor(a) && IsConstant(b)) {
|
---|
981 | var factNode = a as FactorVariableTreeNode;
|
---|
982 | var constNode = b as ConstantTreeNode;
|
---|
983 | return MakeFactor(factNode.Symbol, factNode.VariableName,
|
---|
984 | factNode.Weights.Select(w => Math.Pow(w, 1.0 / Math.Round(constNode.Value))));
|
---|
985 | } else if (IsBinFactor(a) && IsConstant(b)) {
|
---|
986 | var binFactor = a as BinaryFactorVariableTreeNode;
|
---|
987 | var constNode = b as ConstantTreeNode;
|
---|
988 | return MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, Math.Pow(binFactor.Weight, 1.0 / Math.Round(constNode.Value)));
|
---|
989 | } else if (IsConstant(a) && IsFactor(b)) {
|
---|
990 | var constNode = a as ConstantTreeNode;
|
---|
991 | var factNode = b as FactorVariableTreeNode;
|
---|
992 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => Math.Pow(constNode.Value, 1.0 / Math.Round(w))));
|
---|
993 | } else if (IsConstant(a) && IsBinFactor(b)) {
|
---|
994 | var constNode = a as ConstantTreeNode;
|
---|
995 | var factNode = b as BinaryFactorVariableTreeNode;
|
---|
996 | return MakeBinFactor(factNode.Symbol, factNode.VariableName, factNode.VariableValue, Math.Pow(constNode.Value, 1.0 / Math.Round(factNode.Weight)));
|
---|
997 | } else if (IsFactor(a) && IsFactor(b) && AreSameTypeAndVariable(a, b)) {
|
---|
998 | var node0 = a as FactorVariableTreeNode;
|
---|
999 | var node1 = b as FactorVariableTreeNode;
|
---|
1000 | return MakeFactor(node0.Symbol, node0.VariableName, node0.Weights.Zip(node1.Weights, (u, v) => Math.Pow(u, 1.0 / Math.Round(v))));
|
---|
1001 | } else if (IsConstant(b)) {
|
---|
1002 | var constB = b as ConstantTreeNode;
|
---|
1003 | var constBValue = Math.Round(constB.Value);
|
---|
1004 | if (constBValue.IsAlmost(1.0)) {
|
---|
1005 | return a;
|
---|
1006 | } else if (constBValue.IsAlmost(0.0)) {
|
---|
1007 | return MakeConstant(1.0);
|
---|
1008 | } else if (constBValue.IsAlmost(-1.0)) {
|
---|
1009 | return MakeFraction(MakeConstant(1.0), a);
|
---|
1010 | } else if (constBValue < 0) {
|
---|
1011 | var rootNode = rootSymbol.CreateTreeNode();
|
---|
1012 | rootNode.AddSubtree(a);
|
---|
1013 | rootNode.AddSubtree(MakeConstant(-1.0 * constBValue));
|
---|
1014 | return MakeFraction(MakeConstant(1.0), rootNode);
|
---|
1015 | } else {
|
---|
1016 | var rootNode = rootSymbol.CreateTreeNode();
|
---|
1017 | rootNode.AddSubtree(a);
|
---|
1018 | rootNode.AddSubtree(MakeConstant(constBValue));
|
---|
1019 | return rootNode;
|
---|
1020 | }
|
---|
1021 | } else {
|
---|
1022 | var rootNode = rootSymbol.CreateTreeNode();
|
---|
1023 | rootNode.AddSubtree(a);
|
---|
1024 | rootNode.AddSubtree(b);
|
---|
1025 | return rootNode;
|
---|
1026 | }
|
---|
1027 | }
|
---|
1028 |
|
---|
1029 |
|
---|
1030 | private ISymbolicExpressionTreeNode MakePower(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
|
---|
1031 | if (IsConstant(a) && IsConstant(b)) {
|
---|
1032 | var constA = a as ConstantTreeNode;
|
---|
1033 | var constB = b as ConstantTreeNode;
|
---|
1034 | return MakeConstant(Math.Pow(constA.Value, Math.Round(constB.Value)));
|
---|
1035 | } else if (IsFactor(a) && IsConstant(b)) {
|
---|
1036 | var factNode = a as FactorVariableTreeNode;
|
---|
1037 | var constNode = b as ConstantTreeNode;
|
---|
1038 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => Math.Pow(w, Math.Round(constNode.Value))));
|
---|
1039 | } else if (IsBinFactor(a) && IsConstant(b)) {
|
---|
1040 | var binFactor = a as BinaryFactorVariableTreeNode;
|
---|
1041 | var constNode = b as ConstantTreeNode;
|
---|
1042 | return MakeBinFactor(binFactor.Symbol, binFactor.VariableName, binFactor.VariableValue, Math.Pow(binFactor.Weight, Math.Round(constNode.Value)));
|
---|
1043 | } else if (IsConstant(a) && IsFactor(b)) {
|
---|
1044 | var constNode = a as ConstantTreeNode;
|
---|
1045 | var factNode = b as FactorVariableTreeNode;
|
---|
1046 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => Math.Pow(constNode.Value, Math.Round(w))));
|
---|
1047 | } else if (IsConstant(a) && IsBinFactor(b)) {
|
---|
1048 | var constNode = a as ConstantTreeNode;
|
---|
1049 | var factNode = b as BinaryFactorVariableTreeNode;
|
---|
1050 | return MakeBinFactor(factNode.Symbol, factNode.VariableName, factNode.VariableValue, Math.Pow(constNode.Value, Math.Round(factNode.Weight)));
|
---|
1051 | } else if (IsFactor(a) && IsFactor(b) && AreSameTypeAndVariable(a, b)) {
|
---|
1052 | var node0 = a as FactorVariableTreeNode;
|
---|
1053 | var node1 = b as FactorVariableTreeNode;
|
---|
1054 | return MakeFactor(node0.Symbol, node0.VariableName, node0.Weights.Zip(node1.Weights, (u, v) => Math.Pow(u, Math.Round(v))));
|
---|
1055 | } else if (IsConstant(b)) {
|
---|
1056 | var constB = b as ConstantTreeNode;
|
---|
1057 | double exponent = Math.Round(constB.Value);
|
---|
1058 | if (exponent.IsAlmost(0.0)) {
|
---|
1059 | return MakeConstant(1.0);
|
---|
1060 | } else if (exponent.IsAlmost(1.0)) {
|
---|
1061 | return a;
|
---|
1062 | } else if (exponent.IsAlmost(-1.0)) {
|
---|
1063 | return MakeFraction(MakeConstant(1.0), a);
|
---|
1064 | } else if (exponent < 0) {
|
---|
1065 | var powNode = powSymbol.CreateTreeNode();
|
---|
1066 | powNode.AddSubtree(a);
|
---|
1067 | powNode.AddSubtree(MakeConstant(-1.0 * exponent));
|
---|
1068 | return MakeFraction(MakeConstant(1.0), powNode);
|
---|
1069 | } else {
|
---|
1070 | var powNode = powSymbol.CreateTreeNode();
|
---|
1071 | powNode.AddSubtree(a);
|
---|
1072 | powNode.AddSubtree(MakeConstant(exponent));
|
---|
1073 | return powNode;
|
---|
1074 | }
|
---|
1075 | } else {
|
---|
1076 | var powNode = powSymbol.CreateTreeNode();
|
---|
1077 | powNode.AddSubtree(a);
|
---|
1078 | powNode.AddSubtree(b);
|
---|
1079 | return powNode;
|
---|
1080 | }
|
---|
1081 | }
|
---|
1082 |
|
---|
1083 |
|
---|
1084 | // MakeFraction, MakeProduct and MakeSum take two already simplified trees and create a new simplified tree
|
---|
1085 | private ISymbolicExpressionTreeNode MakeFraction(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
|
---|
1086 | if (IsConstant(a) && IsConstant(b)) {
|
---|
1087 | // fold constants
|
---|
1088 | return MakeConstant(((ConstantTreeNode)a).Value / ((ConstantTreeNode)b).Value);
|
---|
1089 | } else if ((IsConstant(a) && !((ConstantTreeNode)a).Value.IsAlmost(1.0))) {
|
---|
1090 | return MakeFraction(MakeConstant(1.0), MakeProduct(b, Invert(a)));
|
---|
1091 | } else if (IsVariableBase(a) && IsConstant(b)) {
|
---|
1092 | // merge constant values into variable weights
|
---|
1093 | var constB = ((ConstantTreeNode)b).Value;
|
---|
1094 | ((VariableTreeNodeBase)a).Weight /= constB;
|
---|
1095 | return a;
|
---|
1096 | } else if (IsFactor(a) && IsConstant(b)) {
|
---|
1097 | var factNode = a as FactorVariableTreeNode;
|
---|
1098 | var constNode = b as ConstantTreeNode;
|
---|
1099 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select(w => w / constNode.Value));
|
---|
1100 | } else if (IsBinFactor(a) && IsConstant(b)) {
|
---|
1101 | var factNode = a as BinaryFactorVariableTreeNode;
|
---|
1102 | var constNode = b as ConstantTreeNode;
|
---|
1103 | return MakeBinFactor(factNode.Symbol, factNode.VariableName, factNode.VariableValue, factNode.Weight / constNode.Value);
|
---|
1104 | } else if (IsFactor(a) && IsFactor(b) && AreSameTypeAndVariable(a, b)) {
|
---|
1105 | var node0 = a as FactorVariableTreeNode;
|
---|
1106 | var node1 = b as FactorVariableTreeNode;
|
---|
1107 | return MakeFactor(node0.Symbol, node0.VariableName, node0.Weights.Zip(node1.Weights, (u, v) => u / v));
|
---|
1108 | } else if (IsFactor(a) && IsBinFactor(b) && ((IVariableTreeNode)a).VariableName == ((IVariableTreeNode)b).VariableName) {
|
---|
1109 | var node0 = a as FactorVariableTreeNode;
|
---|
1110 | var node1 = b as BinaryFactorVariableTreeNode;
|
---|
1111 | var varValues = node0.Symbol.GetVariableValues(node0.VariableName).ToArray();
|
---|
1112 | var wi = Array.IndexOf(varValues, node1.VariableValue);
|
---|
1113 | if (wi < 0) throw new ArgumentException();
|
---|
1114 | var newWeighs = new double[varValues.Length];
|
---|
1115 | node0.Weights.CopyTo(newWeighs, 0);
|
---|
1116 | for (int i = 0; i < newWeighs.Length; i++)
|
---|
1117 | if (wi == i) newWeighs[i] /= node1.Weight;
|
---|
1118 | else newWeighs[i] /= 0.0;
|
---|
1119 | return MakeFactor(node0.Symbol, node0.VariableName, newWeighs);
|
---|
1120 | } else if (IsFactor(a)) {
|
---|
1121 | return MakeFraction(MakeConstant(1.0), MakeProduct(b, Invert(a)));
|
---|
1122 | } else if (IsVariableBase(a) && IsVariableBase(b) && AreSameTypeAndVariable(a, b) && !IsBinFactor(b)) {
|
---|
1123 | // cancel variables (not allowed for bin factors because of division by zero)
|
---|
1124 | var aVar = a as VariableTreeNode;
|
---|
1125 | var bVar = b as VariableTreeNode;
|
---|
1126 | return MakeConstant(aVar.Weight / bVar.Weight);
|
---|
1127 | } else if (IsAddition(a) && IsConstant(b)) {
|
---|
1128 | return a.Subtrees
|
---|
1129 | .Select(x => GetSimplifiedTree(x))
|
---|
1130 | .Select(x => MakeFraction(x, GetSimplifiedTree(b)))
|
---|
1131 | .Aggregate((c, d) => MakeSum(c, d));
|
---|
1132 | } else if (IsMultiplication(a) && IsConstant(b)) {
|
---|
1133 | return MakeProduct(a, Invert(b));
|
---|
1134 | } else if (IsDivision(a) && IsConstant(b)) {
|
---|
1135 | // (a1 / a2) / c => (a1 / (a2 * c))
|
---|
1136 | return MakeFraction(a.GetSubtree(0), MakeProduct(a.GetSubtree(1), b));
|
---|
1137 | } else if (IsDivision(a) && IsDivision(b)) {
|
---|
1138 | // (a1 / a2) / (b1 / b2) =>
|
---|
1139 | return MakeFraction(MakeProduct(a.GetSubtree(0), b.GetSubtree(1)), MakeProduct(a.GetSubtree(1), b.GetSubtree(0)));
|
---|
1140 | } else if (IsDivision(a)) {
|
---|
1141 | // (a1 / a2) / b => (a1 / (a2 * b))
|
---|
1142 | return MakeFraction(a.GetSubtree(0), MakeProduct(a.GetSubtree(1), b));
|
---|
1143 | } else if (IsDivision(b)) {
|
---|
1144 | // a / (b1 / b2) => (a * b2) / b1
|
---|
1145 | return MakeFraction(MakeProduct(a, b.GetSubtree(1)), b.GetSubtree(0));
|
---|
1146 | } else if (IsAnalyticalQuotient(a)) {
|
---|
1147 | return MakeAnalyticalQuotient(a.GetSubtree(0), MakeProduct(a.GetSubtree(1), b));
|
---|
1148 | } else {
|
---|
1149 | var div = divSymbol.CreateTreeNode();
|
---|
1150 | div.AddSubtree(a);
|
---|
1151 | div.AddSubtree(b);
|
---|
1152 | return div;
|
---|
1153 | }
|
---|
1154 | }
|
---|
1155 |
|
---|
1156 | private ISymbolicExpressionTreeNode MakeSum(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
|
---|
1157 | if (IsConstant(a) && IsConstant(b)) {
|
---|
1158 | // fold constants
|
---|
1159 | ((ConstantTreeNode)a).Value += ((ConstantTreeNode)b).Value;
|
---|
1160 | return a;
|
---|
1161 | } else if (IsConstant(a)) {
|
---|
1162 | // c + x => x + c
|
---|
1163 | // b is not constant => make sure constant is on the right
|
---|
1164 | return MakeSum(b, a);
|
---|
1165 | } else if (IsConstant(b) && ((ConstantTreeNode)b).Value.IsAlmost(0.0)) {
|
---|
1166 | // x + 0 => x
|
---|
1167 | return a;
|
---|
1168 | } else if (IsFactor(a) && IsConstant(b)) {
|
---|
1169 | var factNode = a as FactorVariableTreeNode;
|
---|
1170 | var constNode = b as ConstantTreeNode;
|
---|
1171 | return MakeFactor(factNode.Symbol, factNode.VariableName, factNode.Weights.Select((w) => w + constNode.Value));
|
---|
1172 | } else if (IsFactor(a) && IsFactor(b) && AreSameTypeAndVariable(a, b)) {
|
---|
1173 | var node0 = a as FactorVariableTreeNode;
|
---|
1174 | var node1 = b as FactorVariableTreeNode;
|
---|
1175 | return MakeFactor(node0.Symbol, node0.VariableName, node0.Weights.Zip(node1.Weights, (u, v) => u + v));
|
---|
1176 | } else if (IsBinFactor(a) && IsFactor(b)) {
|
---|
1177 | return MakeSum(b, a);
|
---|
1178 | } else if (IsFactor(a) && IsBinFactor(b) &&
|
---|
1179 | ((IVariableTreeNode)a).VariableName == ((IVariableTreeNode)b).VariableName) {
|
---|
1180 | var node0 = a as FactorVariableTreeNode;
|
---|
1181 | var node1 = b as BinaryFactorVariableTreeNode;
|
---|
1182 | var varValues = node0.Symbol.GetVariableValues(node0.VariableName).ToArray();
|
---|
1183 | var wi = Array.IndexOf(varValues, node1.VariableValue);
|
---|
1184 | if (wi < 0) throw new ArgumentException();
|
---|
1185 | var newWeighs = new double[varValues.Length];
|
---|
1186 | node0.Weights.CopyTo(newWeighs, 0);
|
---|
1187 | newWeighs[wi] += node1.Weight;
|
---|
1188 | return MakeFactor(node0.Symbol, node0.VariableName, newWeighs);
|
---|
1189 | } else if (IsAddition(a) && IsAddition(b)) {
|
---|
1190 | // merge additions
|
---|
1191 | var add = addSymbol.CreateTreeNode();
|
---|
1192 | // add all sub trees except for the last
|
---|
1193 | for (int i = 0; i < a.Subtrees.Count() - 1; i++) add.AddSubtree(a.GetSubtree(i));
|
---|
1194 | for (int i = 0; i < b.Subtrees.Count() - 1; i++) add.AddSubtree(b.GetSubtree(i));
|
---|
1195 | if (IsConstant(a.Subtrees.Last()) && IsConstant(b.Subtrees.Last())) {
|
---|
1196 | add.AddSubtree(MakeSum(a.Subtrees.Last(), b.Subtrees.Last()));
|
---|
1197 | } else if (IsConstant(a.Subtrees.Last())) {
|
---|
1198 | add.AddSubtree(b.Subtrees.Last());
|
---|
1199 | add.AddSubtree(a.Subtrees.Last());
|
---|
1200 | } else {
|
---|
1201 | add.AddSubtree(a.Subtrees.Last());
|
---|
1202 | add.AddSubtree(b.Subtrees.Last());
|
---|
1203 | }
|
---|
1204 | MergeVariablesInSum(add);
|
---|
1205 | if (add.Subtrees.Count() == 1) {
|
---|
1206 | return add.GetSubtree(0);
|
---|
1207 | } else {
|
---|
1208 | return add;
|
---|
1209 | }
|
---|
1210 | } else if (IsAddition(b)) {
|
---|
1211 | return MakeSum(b, a);
|
---|
1212 | } else if (IsAddition(a) && IsConstant(b)) {
|
---|
1213 | // a is an addition and b is a constant => append b to a and make sure the constants are merged
|
---|
1214 | var add = addSymbol.CreateTreeNode();
|
---|
1215 | // add all sub trees except for the last
|
---|
1216 | for (int i = 0; i < a.Subtrees.Count() - 1; i++) add.AddSubtree(a.GetSubtree(i));
|
---|
1217 | if (IsConstant(a.Subtrees.Last()))
|
---|
1218 | add.AddSubtree(MakeSum(a.Subtrees.Last(), b));
|
---|
1219 | else {
|
---|
1220 | add.AddSubtree(a.Subtrees.Last());
|
---|
1221 | add.AddSubtree(b);
|
---|
1222 | }
|
---|
1223 | return add;
|
---|
1224 | } else if (IsAddition(a)) {
|
---|
1225 | // a is already an addition => append b
|
---|
1226 | var add = addSymbol.CreateTreeNode();
|
---|
1227 | add.AddSubtree(b);
|
---|
1228 | foreach (var subtree in a.Subtrees) {
|
---|
1229 | add.AddSubtree(subtree);
|
---|
1230 | }
|
---|
1231 | MergeVariablesInSum(add);
|
---|
1232 | if (add.Subtrees.Count() == 1) {
|
---|
1233 | return add.GetSubtree(0);
|
---|
1234 | } else {
|
---|
1235 | return add;
|
---|
1236 | }
|
---|
1237 | } else {
|
---|
1238 | var add = addSymbol.CreateTreeNode();
|
---|
1239 | add.AddSubtree(a);
|
---|
1240 | add.AddSubtree(b);
|
---|
1241 | MergeVariablesInSum(add);
|
---|
1242 | if (add.Subtrees.Count() == 1) {
|
---|
1243 | return add.GetSubtree(0);
|
---|
1244 | } else {
|
---|
1245 | return add;
|
---|
1246 | }
|
---|
1247 | }
|
---|
1248 | }
|
---|
1249 |
|
---|
1250 | // makes sure variable symbols in sums are combined
|
---|
1251 | private void MergeVariablesInSum(ISymbolicExpressionTreeNode sum) {
|
---|
1252 | var subtrees = new List<ISymbolicExpressionTreeNode>(sum.Subtrees);
|
---|
1253 | while (sum.Subtrees.Any()) sum.RemoveSubtree(0);
|
---|
1254 | var groupedVarNodes = from node in subtrees.OfType<IVariableTreeNode>()
|
---|
1255 | where node.SubtreeCount == 0
|
---|
1256 | group node by GroupId(node) into g
|
---|
1257 | select g;
|
---|
1258 | var constant = (from node in subtrees.OfType<ConstantTreeNode>()
|
---|
1259 | select node.Value).DefaultIfEmpty(0.0).Sum();
|
---|
1260 | var unchangedSubtrees = subtrees.Where(t => t.SubtreeCount > 0 || !(t is IVariableTreeNode) && !(t is ConstantTreeNode));
|
---|
1261 |
|
---|
1262 | foreach (var variableNodeGroup in groupedVarNodes) {
|
---|
1263 | var firstNode = variableNodeGroup.First();
|
---|
1264 | if (firstNode is VariableTreeNodeBase) {
|
---|
1265 | var representative = firstNode as VariableTreeNodeBase;
|
---|
1266 | var weightSum = variableNodeGroup.Cast<VariableTreeNodeBase>().Select(t => t.Weight).Sum();
|
---|
1267 | representative.Weight = weightSum;
|
---|
1268 | sum.AddSubtree(representative);
|
---|
1269 | } else if (firstNode is FactorVariableTreeNode) {
|
---|
1270 | var representative = firstNode as FactorVariableTreeNode;
|
---|
1271 | foreach (var node in variableNodeGroup.Skip(1).Cast<FactorVariableTreeNode>()) {
|
---|
1272 | for (int j = 0; j < representative.Weights.Length; j++) {
|
---|
1273 | representative.Weights[j] += node.Weights[j];
|
---|
1274 | }
|
---|
1275 | }
|
---|
1276 | sum.AddSubtree(representative);
|
---|
1277 | }
|
---|
1278 | }
|
---|
1279 | foreach (var unchangedSubtree in unchangedSubtrees)
|
---|
1280 | sum.AddSubtree(unchangedSubtree);
|
---|
1281 | if (!constant.IsAlmost(0.0)) {
|
---|
1282 | sum.AddSubtree(MakeConstant(constant));
|
---|
1283 | }
|
---|
1284 | }
|
---|
1285 |
|
---|
1286 | // nodes referencing variables can be grouped if they have
|
---|
1287 | private string GroupId(IVariableTreeNode node) {
|
---|
1288 | var binaryFactorNode = node as BinaryFactorVariableTreeNode;
|
---|
1289 | var factorNode = node as FactorVariableTreeNode;
|
---|
1290 | var variableNode = node as VariableTreeNode;
|
---|
1291 | var laggedVarNode = node as LaggedVariableTreeNode;
|
---|
1292 | if (variableNode != null) {
|
---|
1293 | return "var " + variableNode.VariableName;
|
---|
1294 | } else if (binaryFactorNode != null) {
|
---|
1295 | return "binfactor " + binaryFactorNode.VariableName + " " + binaryFactorNode.VariableValue;
|
---|
1296 | } else if (factorNode != null) {
|
---|
1297 | return "factor " + factorNode.VariableName;
|
---|
1298 | } else if (laggedVarNode != null) {
|
---|
1299 | return "lagged " + laggedVarNode.VariableName + " " + laggedVarNode.Lag;
|
---|
1300 | } else {
|
---|
1301 | throw new NotSupportedException();
|
---|
1302 | }
|
---|
1303 | }
|
---|
1304 |
|
---|
1305 |
|
---|
1306 | private ISymbolicExpressionTreeNode MakeProduct(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
|
---|
1307 | if (IsConstant(a) && IsConstant(b)) {
|
---|
1308 | // fold constants
|
---|
1309 | return MakeConstant(((ConstantTreeNode)a).Value * ((ConstantTreeNode)b).Value);
|
---|
1310 | } else if (IsConstant(a)) {
|
---|
1311 | // a * $ => $ * a
|
---|
1312 | return MakeProduct(b, a);
|
---|
1313 | } else if (IsFactor(a) && IsFactor(b) && AreSameTypeAndVariable(a, b)) {
|
---|
1314 | var node0 = a as FactorVariableTreeNode;
|
---|
1315 | var node1 = b as FactorVariableTreeNode;
|
---|
1316 | return MakeFactor(node0.Symbol, node0.VariableName, node0.Weights.Zip(node1.Weights, (u, v) => u * v));
|
---|
1317 | } else if (IsBinFactor(a) && IsBinFactor(b) && AreSameTypeAndVariable(a, b)) {
|
---|
1318 | var node0 = a as BinaryFactorVariableTreeNode;
|
---|
1319 | var node1 = b as BinaryFactorVariableTreeNode;
|
---|
1320 | return MakeBinFactor(node0.Symbol, node0.VariableName, node0.VariableValue, node0.Weight * node1.Weight);
|
---|
1321 | } else if (IsFactor(a) && IsConstant(b)) {
|
---|
1322 | var node0 = a as FactorVariableTreeNode;
|
---|
1323 | var node1 = b as ConstantTreeNode;
|
---|
1324 | return MakeFactor(node0.Symbol, node0.VariableName, node0.Weights.Select(w => w * node1.Value));
|
---|
1325 | } else if (IsBinFactor(a) && IsConstant(b)) {
|
---|
1326 | var node0 = a as BinaryFactorVariableTreeNode;
|
---|
1327 | var node1 = b as ConstantTreeNode;
|
---|
1328 | return MakeBinFactor(node0.Symbol, node0.VariableName, node0.VariableValue, node0.Weight * node1.Value);
|
---|
1329 | } else if (IsBinFactor(a) && IsFactor(b)) {
|
---|
1330 | return MakeProduct(b, a);
|
---|
1331 | } else if (IsFactor(a) && IsBinFactor(b) &&
|
---|
1332 | ((IVariableTreeNode)a).VariableName == ((IVariableTreeNode)b).VariableName) {
|
---|
1333 | var node0 = a as FactorVariableTreeNode;
|
---|
1334 | var node1 = b as BinaryFactorVariableTreeNode;
|
---|
1335 | var varValues = node0.Symbol.GetVariableValues(node0.VariableName).ToArray();
|
---|
1336 | var wi = Array.IndexOf(varValues, node1.VariableValue);
|
---|
1337 | if (wi < 0) throw new ArgumentException();
|
---|
1338 | return MakeBinFactor(node1.Symbol, node1.VariableName, node1.VariableValue, node1.Weight * node0.Weights[wi]);
|
---|
1339 | } else if (IsConstant(b) && ((ConstantTreeNode)b).Value.IsAlmost(1.0)) {
|
---|
1340 | // $ * 1.0 => $
|
---|
1341 | return a;
|
---|
1342 | } else if (IsConstant(b) && ((ConstantTreeNode)b).Value.IsAlmost(0.0)) {
|
---|
1343 | return MakeConstant(0);
|
---|
1344 | } else if (IsConstant(b) && IsVariableBase(a)) {
|
---|
1345 | // multiply constants into variables weights
|
---|
1346 | ((VariableTreeNodeBase)a).Weight *= ((ConstantTreeNode)b).Value;
|
---|
1347 | return a;
|
---|
1348 | } else if (IsConstant(b) && IsAddition(a) ||
|
---|
1349 | IsFactor(b) && IsAddition(a) ||
|
---|
1350 | IsBinFactor(b) && IsAddition(a)) {
|
---|
1351 | // multiply constants into additions
|
---|
1352 | return a.Subtrees.Select(x => MakeProduct(GetSimplifiedTree(x), GetSimplifiedTree(b))).Aggregate((c, d) => MakeSum(c, d));
|
---|
1353 | } else if (IsDivision(a) && IsDivision(b)) {
|
---|
1354 | // (a1 / a2) * (b1 / b2) => (a1 * b1) / (a2 * b2)
|
---|
1355 | return MakeFraction(MakeProduct(a.GetSubtree(0), b.GetSubtree(0)), MakeProduct(a.GetSubtree(1), b.GetSubtree(1)));
|
---|
1356 | } else if (IsDivision(a)) {
|
---|
1357 | // (a1 / a2) * b => (a1 * b) / a2
|
---|
1358 | return MakeFraction(MakeProduct(a.GetSubtree(0), b), a.GetSubtree(1));
|
---|
1359 | } else if (IsDivision(b)) {
|
---|
1360 | // a * (b1 / b2) => (b1 * a) / b2
|
---|
1361 | return MakeFraction(MakeProduct(b.GetSubtree(0), a), b.GetSubtree(1));
|
---|
1362 | } else if (IsMultiplication(a) && IsMultiplication(b)) {
|
---|
1363 | // merge multiplications (make sure constants are merged)
|
---|
1364 | var mul = mulSymbol.CreateTreeNode();
|
---|
1365 | for (int i = 0; i < a.Subtrees.Count(); i++) mul.AddSubtree(a.GetSubtree(i));
|
---|
1366 | for (int i = 0; i < b.Subtrees.Count(); i++) mul.AddSubtree(b.GetSubtree(i));
|
---|
1367 | MergeVariablesAndConstantsInProduct(mul);
|
---|
1368 | return mul;
|
---|
1369 | } else if (IsMultiplication(b)) {
|
---|
1370 | return MakeProduct(b, a);
|
---|
1371 | } else if (IsMultiplication(a)) {
|
---|
1372 | // a is already an multiplication => append b
|
---|
1373 | a.AddSubtree(GetSimplifiedTree(b));
|
---|
1374 | MergeVariablesAndConstantsInProduct(a);
|
---|
1375 | return a;
|
---|
1376 | } else if (IsAbsolute(a) && IsAbsolute(b)) {
|
---|
1377 | return MakeAbs(MakeProduct(a.GetSubtree(0), b.GetSubtree(0)));
|
---|
1378 | } else if (IsAbsolute(a) && IsConstant(b)) {
|
---|
1379 | var constNode = b as ConstantTreeNode;
|
---|
1380 | var posF = Math.Abs(constNode.Value);
|
---|
1381 | if (constNode.Value > 0) {
|
---|
1382 | return MakeAbs(MakeProduct(a.GetSubtree(0), MakeConstant(posF)));
|
---|
1383 | } else {
|
---|
1384 | var mul = mulSymbol.CreateTreeNode();
|
---|
1385 | mul.AddSubtree(MakeAbs(MakeProduct(a.GetSubtree(0), MakeConstant(posF))));
|
---|
1386 | mul.AddSubtree(MakeConstant(-1.0));
|
---|
1387 | return mul;
|
---|
1388 | }
|
---|
1389 | } else if (IsAnalyticalQuotient(a)) {
|
---|
1390 | return MakeAnalyticalQuotient(MakeProduct(a.GetSubtree(0), b), a.GetSubtree(1));
|
---|
1391 | } else {
|
---|
1392 | var mul = mulSymbol.CreateTreeNode();
|
---|
1393 | mul.AddSubtree(a);
|
---|
1394 | mul.AddSubtree(b);
|
---|
1395 | MergeVariablesAndConstantsInProduct(mul);
|
---|
1396 | return mul;
|
---|
1397 | }
|
---|
1398 | }
|
---|
1399 |
|
---|
1400 | private ISymbolicExpressionTreeNode MakeSumAggregation(ISymbolicExpressionTreeNode node) {
|
---|
1401 | if (IsConstant(node)) { // assumes scalar constant
|
---|
1402 | return node;
|
---|
1403 | } else if (IsAddition(node) || IsSubtraction(node)) {
|
---|
1404 | var terms = node.Subtrees;
|
---|
1405 | if (IsSubtraction(node)) terms = InvertNodes(terms, Negate);
|
---|
1406 |
|
---|
1407 | var scalarTerms = terms.Where(IsScalarNode).ToList();
|
---|
1408 | var remainingTerms = terms.Except(scalarTerms).ToList();
|
---|
1409 |
|
---|
1410 | if (scalarTerms.Any() && remainingTerms.Any()) {
|
---|
1411 | var scalarNode = scalarTerms.Aggregate(MakeSum);
|
---|
1412 | var vectorNode = remainingTerms.Aggregate(MakeSum);
|
---|
1413 |
|
---|
1414 | var lengthNode = MakeLengthAggregation((ISymbolicExpressionTreeNode)vectorNode.Clone());
|
---|
1415 | var scalarMulNode = MakeProduct(scalarNode, lengthNode);
|
---|
1416 |
|
---|
1417 | var sumNode = MakeSumAggregation(vectorNode);
|
---|
1418 |
|
---|
1419 | return MakeSum(scalarMulNode, sumNode);
|
---|
1420 | } else if (scalarTerms.Any()) {
|
---|
1421 | var scalarNode = scalarTerms.Aggregate(MakeSum);
|
---|
1422 | return scalarNode;
|
---|
1423 | } else if (remainingTerms.Any()) {
|
---|
1424 | var vectorNode = remainingTerms.Aggregate(MakeSum);
|
---|
1425 | var sumNode = sumSymbol.CreateTreeNode();
|
---|
1426 | sumNode.AddSubtree(vectorNode);
|
---|
1427 | return sumNode;
|
---|
1428 | } else
|
---|
1429 | throw new InvalidOperationException("Addition does not contain any terms to simplify.");
|
---|
1430 | } else if (IsMultiplication(node) || IsDivision(node)) {
|
---|
1431 | var factors = node.Subtrees;
|
---|
1432 | if (IsDivision(node)) factors = InvertNodes(factors, Invert);
|
---|
1433 |
|
---|
1434 | var scalarFactors = factors.Where(IsScalarNode).ToList();
|
---|
1435 | var remainingFactors = factors.Except(scalarFactors).ToList();
|
---|
1436 |
|
---|
1437 | if (scalarFactors.Any() && remainingFactors.Any()) {
|
---|
1438 | var scalarNode = scalarFactors.Aggregate(MakeProduct);
|
---|
1439 | var vectorNode = remainingFactors.Aggregate(MakeProduct);
|
---|
1440 |
|
---|
1441 | var sumNode = MakeSumAggregation(vectorNode);
|
---|
1442 |
|
---|
1443 | return MakeProduct(scalarNode, sumNode);
|
---|
1444 | } else if (scalarFactors.Any()) {
|
---|
1445 | var scalarNode = scalarFactors.Aggregate(MakeProduct);
|
---|
1446 | return scalarNode;
|
---|
1447 | } else if (remainingFactors.Any()) {
|
---|
1448 | var vectorNode = remainingFactors.Aggregate(MakeProduct);
|
---|
1449 | var sumNode = sumSymbol.CreateTreeNode();
|
---|
1450 | sumNode.AddSubtree(vectorNode);
|
---|
1451 | return sumNode;
|
---|
1452 | } else
|
---|
1453 | throw new InvalidOperationException("Multiplication does not contain any terms to simplify.");
|
---|
1454 | } else if (IsVariableBase(node)) { // weight is like multiplication
|
---|
1455 | var variableNode = (VariableTreeNodeBase)node;
|
---|
1456 | var weight = variableNode.Weight;
|
---|
1457 | variableNode.Weight = 1.0;
|
---|
1458 | var sumNode = sumSymbol.CreateTreeNode();
|
---|
1459 | sumNode.AddSubtree(node);
|
---|
1460 | return MakeProduct(MakeConstant(weight), sumNode);
|
---|
1461 | } else {
|
---|
1462 | var sumNode = sumSymbol.CreateTreeNode();
|
---|
1463 | sumNode.AddSubtree(node);
|
---|
1464 | return sumNode;
|
---|
1465 | }
|
---|
1466 | }
|
---|
1467 |
|
---|
1468 | private ISymbolicExpressionTreeNode MakeMeanAggregation(ISymbolicExpressionTreeNode node) {
|
---|
1469 | if (IsConstant(node)) { // assumes scalar constant
|
---|
1470 | return node;
|
---|
1471 | } else if (IsAddition(node) || IsSubtraction(node)) {
|
---|
1472 | var terms = node.Subtrees;
|
---|
1473 | if (IsSubtraction(node)) terms = InvertNodes(terms, Negate);
|
---|
1474 |
|
---|
1475 | var scalarTerms = terms.Where(IsScalarNode).ToList();
|
---|
1476 | var remainingTerms = terms.Except(scalarTerms).ToList();
|
---|
1477 |
|
---|
1478 | if (scalarTerms.Any() && remainingTerms.Any()) {
|
---|
1479 | var scalarNode = scalarTerms.Aggregate(MakeSum);
|
---|
1480 | var vectorNode = remainingTerms.Aggregate(MakeSum);
|
---|
1481 |
|
---|
1482 | var meanNode = MakeMeanAggregation(vectorNode);
|
---|
1483 |
|
---|
1484 | return MakeSum(scalarNode, meanNode);
|
---|
1485 | } else if (scalarTerms.Any()) {
|
---|
1486 | var scalarNode = scalarTerms.Aggregate(MakeSum);
|
---|
1487 | return scalarNode;
|
---|
1488 | } else if (remainingTerms.Any()) {
|
---|
1489 | var vectorNode = remainingTerms.Aggregate(MakeSum);
|
---|
1490 | var meanNode = meanSymbol.CreateTreeNode();
|
---|
1491 | meanNode.AddSubtree(vectorNode);
|
---|
1492 | return meanNode;
|
---|
1493 | } else
|
---|
1494 | throw new InvalidOperationException("Addition does not contain any terms to simplify.");
|
---|
1495 | } else if (IsMultiplication(node) || IsDivision(node)) {
|
---|
1496 | var factors = node.Subtrees;
|
---|
1497 | if (IsDivision(node)) factors = InvertNodes(factors, Invert);
|
---|
1498 |
|
---|
1499 | var scalarFactors = factors.Where(IsScalarNode).ToList();
|
---|
1500 | var remainingFactors = factors.Except(scalarFactors).ToList();
|
---|
1501 |
|
---|
1502 | if (scalarFactors.Any() && remainingFactors.Any()) {
|
---|
1503 | var scalarNode = scalarFactors.Aggregate(MakeProduct);
|
---|
1504 | var vectorNode = remainingFactors.Aggregate(MakeProduct);
|
---|
1505 |
|
---|
1506 | var meanNode = MakeMeanAggregation(vectorNode);
|
---|
1507 |
|
---|
1508 | return MakeProduct(scalarNode, meanNode);
|
---|
1509 | } else if (scalarFactors.Any()) {
|
---|
1510 | var scalarNode = scalarFactors.Aggregate(MakeProduct);
|
---|
1511 | return scalarNode;
|
---|
1512 | } else if (remainingFactors.Any()) {
|
---|
1513 | var vectorNode = remainingFactors.Aggregate(MakeProduct);
|
---|
1514 | var meanNode = meanSymbol.CreateTreeNode();
|
---|
1515 | meanNode.AddSubtree(vectorNode);
|
---|
1516 | return meanNode;
|
---|
1517 | } else
|
---|
1518 | throw new InvalidOperationException("Multiplication does not contain any terms to simplify.");
|
---|
1519 | } else if (IsVariableBase(node)) { // weight is like multiplication
|
---|
1520 | var variableNode = (VariableTreeNodeBase)node;
|
---|
1521 | var weight = variableNode.Weight;
|
---|
1522 | variableNode.Weight = 1.0;
|
---|
1523 | var meanNode = meanSymbol.CreateTreeNode();
|
---|
1524 | meanNode.AddSubtree(node);
|
---|
1525 | return MakeProduct(MakeConstant(weight), meanNode);
|
---|
1526 | } else {
|
---|
1527 | var meanNode = meanSymbol.CreateTreeNode();
|
---|
1528 | meanNode.AddSubtree(node);
|
---|
1529 | return meanNode;
|
---|
1530 | }
|
---|
1531 | }
|
---|
1532 |
|
---|
1533 | private ISymbolicExpressionTreeNode MakeLengthAggregation(ISymbolicExpressionTreeNode node) {
|
---|
1534 | if (IsConstant(node)) { // assumes scalar constant
|
---|
1535 | return MakeConstant(1.0);
|
---|
1536 | } else if (IsAddition(node) || IsSubtraction(node)) {
|
---|
1537 | var terms = node.Subtrees;
|
---|
1538 | if (IsSubtraction(node)) terms = InvertNodes(terms, Negate);
|
---|
1539 |
|
---|
1540 | var scalarTerms = terms.Where(IsScalarNode).ToList();
|
---|
1541 | var remainingTerms = terms.Except(scalarTerms).ToList();
|
---|
1542 |
|
---|
1543 | if (remainingTerms.Any()) {
|
---|
1544 | var vectorNode = remainingTerms.Aggregate(MakeSum);
|
---|
1545 |
|
---|
1546 | var lengthNode = lengthSymbol.CreateTreeNode();
|
---|
1547 | lengthNode.AddSubtree(vectorNode);
|
---|
1548 |
|
---|
1549 | return lengthNode;
|
---|
1550 | } else if (scalarTerms.Any()) {
|
---|
1551 | return MakeConstant(1.0);
|
---|
1552 | } else
|
---|
1553 | throw new InvalidOperationException("Addition does not contain any terms to simplify.");
|
---|
1554 | } else if (IsMultiplication(node) || IsDivision(node)) {
|
---|
1555 | var factors = node.Subtrees;
|
---|
1556 | if (IsDivision(node)) factors = InvertNodes(factors, Invert);
|
---|
1557 |
|
---|
1558 | var scalarFactors = factors.Where(IsScalarNode).ToList();
|
---|
1559 | var remainingFactors = factors.Except(scalarFactors).ToList();
|
---|
1560 |
|
---|
1561 | if (remainingFactors.Any()) {
|
---|
1562 | var vectorNode = remainingFactors.Aggregate(MakeProduct);
|
---|
1563 |
|
---|
1564 | var lengthNode = lengthSymbol.CreateTreeNode();
|
---|
1565 | lengthNode.AddSubtree(vectorNode);
|
---|
1566 |
|
---|
1567 | return lengthNode;
|
---|
1568 | } else if (scalarFactors.Any()) {
|
---|
1569 | return MakeConstant(1.0);
|
---|
1570 | } else
|
---|
1571 | throw new InvalidOperationException("Multiplication does not contain any terms to simplify.");
|
---|
1572 | } else if (IsVariableBase(node)) { // weight is like multiplication
|
---|
1573 | var variableNode = (VariableTreeNodeBase)node;
|
---|
1574 | variableNode.Weight = 1.0;
|
---|
1575 | var lengthNode = lengthSymbol.CreateTreeNode();
|
---|
1576 | lengthNode.AddSubtree(node);
|
---|
1577 | return lengthNode;
|
---|
1578 | } else {
|
---|
1579 | var lengthNode = lengthSymbol.CreateTreeNode();
|
---|
1580 | lengthNode.AddSubtree(node);
|
---|
1581 | return lengthNode;
|
---|
1582 | }
|
---|
1583 | }
|
---|
1584 |
|
---|
1585 | private ISymbolicExpressionTreeNode MakeStandardDeviationAggregation(ISymbolicExpressionTreeNode node) {
|
---|
1586 | if (IsConstant(node)) {
|
---|
1587 | return MakeConstant(0.0);
|
---|
1588 | } else if (IsMultiplication(node) || IsDivision(node)) {
|
---|
1589 | var factors = node.Subtrees;
|
---|
1590 | if (IsDivision(node)) factors = InvertNodes(factors, Invert);
|
---|
1591 |
|
---|
1592 | var scalarFactors = factors.Where(IsScalarNode).ToList();
|
---|
1593 | var remainingFactors = factors.Except(scalarFactors).ToList();
|
---|
1594 |
|
---|
1595 | if (scalarFactors.Any() && remainingFactors.Any()) {
|
---|
1596 | var scalarNode = scalarFactors.Aggregate(MakeProduct);
|
---|
1597 | var vectorNode = remainingFactors.Aggregate(MakeProduct);
|
---|
1598 |
|
---|
1599 | var stdevNode = MakeStandardDeviationAggregation(vectorNode);
|
---|
1600 |
|
---|
1601 | return MakeProduct(scalarNode, stdevNode);
|
---|
1602 | } else if (scalarFactors.Any()) {
|
---|
1603 | var scalarNode = scalarFactors.Aggregate(MakeProduct);
|
---|
1604 | return scalarNode;
|
---|
1605 | } else if (remainingFactors.Any()) {
|
---|
1606 | var vectorNode = remainingFactors.Aggregate(MakeProduct);
|
---|
1607 | var stdevNode = standardDeviationSymbol.CreateTreeNode();
|
---|
1608 | stdevNode.AddSubtree(vectorNode);
|
---|
1609 | return stdevNode;
|
---|
1610 | } else
|
---|
1611 | throw new InvalidOperationException("Multiplication does not contain any terms to simplify.");
|
---|
1612 | } else if (IsVariableBase(node)) { // weight is like multiplication
|
---|
1613 | var variableNode = (VariableTreeNodeBase)node;
|
---|
1614 | var weight = variableNode.Weight;
|
---|
1615 | variableNode.Weight = 1.0;
|
---|
1616 | var stdevNode = standardDeviationSymbol.CreateTreeNode();
|
---|
1617 | stdevNode.AddSubtree(node);
|
---|
1618 | return MakeProduct(MakeConstant(weight), stdevNode);
|
---|
1619 | } else {
|
---|
1620 | var stdevNode = standardDeviationSymbol.CreateTreeNode();
|
---|
1621 | stdevNode.AddSubtree(node);
|
---|
1622 | return stdevNode;
|
---|
1623 | }
|
---|
1624 | }
|
---|
1625 |
|
---|
1626 | private ISymbolicExpressionTreeNode MakeVarianceAggregation(ISymbolicExpressionTreeNode node) {
|
---|
1627 | if (IsConstant(node)) {
|
---|
1628 | return MakeConstant(0.0);
|
---|
1629 | } else if (IsMultiplication(node) || IsDivision(node)) {
|
---|
1630 | var factors = node.Subtrees;
|
---|
1631 | if (IsDivision(node)) factors = InvertNodes(factors, Invert);
|
---|
1632 |
|
---|
1633 | var scalarFactors = factors.Where(IsScalarNode).ToList();
|
---|
1634 | var remainingFactors = factors.Except(scalarFactors).ToList();
|
---|
1635 |
|
---|
1636 | if (scalarFactors.Any() && remainingFactors.Any()) {
|
---|
1637 | var scalarNode = scalarFactors.Aggregate(MakeProduct);
|
---|
1638 | var vectorNode = remainingFactors.Aggregate(MakeProduct);
|
---|
1639 |
|
---|
1640 | var varNode = MakeVarianceAggregation(vectorNode);
|
---|
1641 |
|
---|
1642 | return MakeProduct(MakeSquare(scalarNode), varNode);
|
---|
1643 | } else if (scalarFactors.Any()) {
|
---|
1644 | var scalarNode = scalarFactors.Aggregate(MakeProduct);
|
---|
1645 | return MakeSquare(scalarNode);
|
---|
1646 | } else if (remainingFactors.Any()) {
|
---|
1647 | var vectorNode = remainingFactors.Aggregate(MakeProduct);
|
---|
1648 | var varNode = varianceSymbol.CreateTreeNode();
|
---|
1649 | varNode.AddSubtree(vectorNode);
|
---|
1650 | return varNode;
|
---|
1651 | } else
|
---|
1652 | throw new InvalidOperationException("Multiplication does not contain any terms to simplify.");
|
---|
1653 | } else if (IsVariableBase(node)) { // weight is like multiplication
|
---|
1654 | var variableNode = (VariableTreeNodeBase)node;
|
---|
1655 | var weight = variableNode.Weight;
|
---|
1656 | variableNode.Weight = 1.0;
|
---|
1657 | var varNode = varianceSymbol.CreateTreeNode();
|
---|
1658 | varNode.AddSubtree(node);
|
---|
1659 | return MakeProduct(MakeSquare(MakeConstant(weight)), varNode);
|
---|
1660 | } else {
|
---|
1661 | var varNode = varianceSymbol.CreateTreeNode();
|
---|
1662 | varNode.AddSubtree(node);
|
---|
1663 | return varNode;
|
---|
1664 | }
|
---|
1665 | }
|
---|
1666 | #endregion
|
---|
1667 |
|
---|
1668 | #region helper functions
|
---|
1669 |
|
---|
1670 | private bool ContainsVariableCondition(ISymbolicExpressionTreeNode node) {
|
---|
1671 | if (node.Symbol is VariableCondition) return true;
|
---|
1672 | foreach (var subtree in node.Subtrees)
|
---|
1673 | if (ContainsVariableCondition(subtree)) return true;
|
---|
1674 | return false;
|
---|
1675 | }
|
---|
1676 |
|
---|
1677 | private ISymbolicExpressionTreeNode AddLagToDynamicNodes(ISymbolicExpressionTreeNode node, int lag) {
|
---|
1678 | var laggedTreeNode = node as ILaggedTreeNode;
|
---|
1679 | var variableNode = node as VariableTreeNode;
|
---|
1680 | var variableConditionNode = node as VariableConditionTreeNode;
|
---|
1681 | if (laggedTreeNode != null)
|
---|
1682 | laggedTreeNode.Lag += lag;
|
---|
1683 | else if (variableNode != null) {
|
---|
1684 | var laggedVariableNode = (LaggedVariableTreeNode)laggedVariableSymbol.CreateTreeNode();
|
---|
1685 | laggedVariableNode.Lag = lag;
|
---|
1686 | laggedVariableNode.VariableName = variableNode.VariableName;
|
---|
1687 | return laggedVariableNode;
|
---|
1688 | } else if (variableConditionNode != null) {
|
---|
1689 | throw new NotSupportedException("Removal of time lags around variable condition symbols is not allowed.");
|
---|
1690 | }
|
---|
1691 | var subtrees = new List<ISymbolicExpressionTreeNode>(node.Subtrees);
|
---|
1692 | while (node.SubtreeCount > 0) node.RemoveSubtree(0);
|
---|
1693 | foreach (var subtree in subtrees) {
|
---|
1694 | node.AddSubtree(AddLagToDynamicNodes(subtree, lag));
|
---|
1695 | }
|
---|
1696 | return node;
|
---|
1697 | }
|
---|
1698 |
|
---|
1699 | private bool AreSameTypeAndVariable(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
|
---|
1700 | return GroupId((IVariableTreeNode)a) == GroupId((IVariableTreeNode)b);
|
---|
1701 | }
|
---|
1702 |
|
---|
1703 | // helper to combine the constant factors in products and to combine variables (powers of 2, 3...)
|
---|
1704 | private void MergeVariablesAndConstantsInProduct(ISymbolicExpressionTreeNode prod) {
|
---|
1705 | var subtrees = new List<ISymbolicExpressionTreeNode>(prod.Subtrees);
|
---|
1706 | while (prod.Subtrees.Any()) prod.RemoveSubtree(0);
|
---|
1707 | var groupedVarNodes = from node in subtrees.OfType<IVariableTreeNode>()
|
---|
1708 | where node.SubtreeCount == 0
|
---|
1709 | group node by GroupId(node) into g
|
---|
1710 | orderby g.Count()
|
---|
1711 | select g;
|
---|
1712 | var constantProduct = (from node in subtrees.OfType<VariableTreeNodeBase>()
|
---|
1713 | select node.Weight)
|
---|
1714 | .Concat(from node in subtrees.OfType<ConstantTreeNode>()
|
---|
1715 | select node.Value)
|
---|
1716 | .DefaultIfEmpty(1.0)
|
---|
1717 | .Aggregate((c1, c2) => c1 * c2);
|
---|
1718 |
|
---|
1719 | var unchangedSubtrees = from tree in subtrees
|
---|
1720 | where tree.SubtreeCount > 0 || !(tree is IVariableTreeNode) && !(tree is ConstantTreeNode)
|
---|
1721 | select tree;
|
---|
1722 |
|
---|
1723 | foreach (var variableNodeGroup in groupedVarNodes) {
|
---|
1724 | var firstNode = variableNodeGroup.First();
|
---|
1725 | if (firstNode is VariableTreeNodeBase) {
|
---|
1726 | var representative = (VariableTreeNodeBase)firstNode;
|
---|
1727 | representative.Weight = 1.0;
|
---|
1728 | if (variableNodeGroup.Count() > 1) {
|
---|
1729 | var poly = mulSymbol.CreateTreeNode();
|
---|
1730 | for (int p = 0; p < variableNodeGroup.Count(); p++) {
|
---|
1731 | poly.AddSubtree((ISymbolicExpressionTreeNode)representative.Clone());
|
---|
1732 | }
|
---|
1733 | prod.AddSubtree(poly);
|
---|
1734 | } else {
|
---|
1735 | prod.AddSubtree(representative);
|
---|
1736 | }
|
---|
1737 | } else if (firstNode is FactorVariableTreeNode) {
|
---|
1738 | var representative = (FactorVariableTreeNode)firstNode;
|
---|
1739 | foreach (var node in variableNodeGroup.Skip(1).Cast<FactorVariableTreeNode>()) {
|
---|
1740 | for (int j = 0; j < representative.Weights.Length; j++) {
|
---|
1741 | representative.Weights[j] *= node.Weights[j];
|
---|
1742 | }
|
---|
1743 | }
|
---|
1744 | for (int j = 0; j < representative.Weights.Length; j++) {
|
---|
1745 | representative.Weights[j] *= constantProduct;
|
---|
1746 | }
|
---|
1747 | constantProduct = 1.0;
|
---|
1748 | // if the product already contains a factor it is not necessary to multiply a constant below
|
---|
1749 | prod.AddSubtree(representative);
|
---|
1750 | }
|
---|
1751 | }
|
---|
1752 |
|
---|
1753 | foreach (var unchangedSubtree in unchangedSubtrees)
|
---|
1754 | prod.AddSubtree(unchangedSubtree);
|
---|
1755 |
|
---|
1756 | if (!constantProduct.IsAlmost(1.0)) {
|
---|
1757 | prod.AddSubtree(MakeConstant(constantProduct));
|
---|
1758 | }
|
---|
1759 | }
|
---|
1760 |
|
---|
1761 |
|
---|
1762 | /// <summary>
|
---|
1763 | /// x => x * -1
|
---|
1764 | /// Is only used in cases where it is not necessary to create new tree nodes. Manipulates x directly.
|
---|
1765 | /// </summary>
|
---|
1766 | /// <param name="x"></param>
|
---|
1767 | /// <returns>-x</returns>
|
---|
1768 | private ISymbolicExpressionTreeNode Negate(ISymbolicExpressionTreeNode x) {
|
---|
1769 | if (IsConstant(x)) {
|
---|
1770 | ((ConstantTreeNode)x).Value *= -1;
|
---|
1771 | } else if (IsVariableBase(x)) {
|
---|
1772 | var variableTree = (VariableTreeNodeBase)x;
|
---|
1773 | variableTree.Weight *= -1.0;
|
---|
1774 | } else if (IsFactor(x)) {
|
---|
1775 | var factorNode = (FactorVariableTreeNode)x;
|
---|
1776 | for (int i = 0; i < factorNode.Weights.Length; i++) factorNode.Weights[i] *= -1;
|
---|
1777 | } else if (IsBinFactor(x)) {
|
---|
1778 | var factorNode = (BinaryFactorVariableTreeNode)x;
|
---|
1779 | factorNode.Weight *= -1;
|
---|
1780 | } else if (IsAddition(x)) {
|
---|
1781 | // (x0 + x1 + .. + xn) * -1 => (-x0 + -x1 + .. + -xn)
|
---|
1782 | var subtrees = new List<ISymbolicExpressionTreeNode>(x.Subtrees);
|
---|
1783 | while (x.Subtrees.Any()) x.RemoveSubtree(0);
|
---|
1784 | foreach (var subtree in subtrees) {
|
---|
1785 | x.AddSubtree(Negate(subtree));
|
---|
1786 | }
|
---|
1787 | } else if (IsMultiplication(x) || IsDivision(x)) {
|
---|
1788 | // x0 * x1 * .. * xn * -1 => x0 * x1 * .. * -xn
|
---|
1789 | var lastSubTree = x.Subtrees.Last();
|
---|
1790 | x.RemoveSubtree(x.SubtreeCount - 1);
|
---|
1791 | x.AddSubtree(Negate(lastSubTree)); // last is maybe a constant, prefer to negate the constant
|
---|
1792 | } else {
|
---|
1793 | // any other function
|
---|
1794 | return MakeProduct(x, MakeConstant(-1));
|
---|
1795 | }
|
---|
1796 | return x;
|
---|
1797 | }
|
---|
1798 |
|
---|
1799 | /// <summary>
|
---|
1800 | /// x => 1/x
|
---|
1801 | /// Must create new tree nodes
|
---|
1802 | /// </summary>
|
---|
1803 | /// <param name="x"></param>
|
---|
1804 | /// <returns></returns>
|
---|
1805 | private ISymbolicExpressionTreeNode Invert(ISymbolicExpressionTreeNode x) {
|
---|
1806 | if (IsConstant(x)) {
|
---|
1807 | return MakeConstant(1.0 / ((ConstantTreeNode)x).Value);
|
---|
1808 | } else if (IsFactor(x)) {
|
---|
1809 | var factorNode = (FactorVariableTreeNode)x;
|
---|
1810 | return MakeFactor(factorNode.Symbol, factorNode.VariableName, factorNode.Weights.Select(w => 1.0 / w));
|
---|
1811 | } else if (IsDivision(x)) {
|
---|
1812 | return MakeFraction(x.GetSubtree(1), x.GetSubtree(0));
|
---|
1813 | } else {
|
---|
1814 | // any other function
|
---|
1815 | return MakeFraction(MakeConstant(1), x);
|
---|
1816 | }
|
---|
1817 | }
|
---|
1818 |
|
---|
1819 | private static ISymbolicExpressionTreeNode MakeConstant(double value) {
|
---|
1820 | ConstantTreeNode constantTreeNode = (ConstantTreeNode)(constSymbol.CreateTreeNode());
|
---|
1821 | constantTreeNode.Value = value;
|
---|
1822 | return constantTreeNode;
|
---|
1823 | }
|
---|
1824 |
|
---|
1825 | private static ISymbolicExpressionTreeNode MakeFactor(FactorVariable sy, string variableName, IEnumerable<double> weights) {
|
---|
1826 | var tree = (FactorVariableTreeNode)sy.CreateTreeNode();
|
---|
1827 | tree.VariableName = variableName;
|
---|
1828 | tree.Weights = weights.ToArray();
|
---|
1829 | return tree;
|
---|
1830 | }
|
---|
1831 | private static ISymbolicExpressionTreeNode MakeBinFactor(BinaryFactorVariable sy, string variableName, string variableValue, double weight) {
|
---|
1832 | var tree = (BinaryFactorVariableTreeNode)sy.CreateTreeNode();
|
---|
1833 | tree.VariableName = variableName;
|
---|
1834 | tree.VariableValue = variableValue;
|
---|
1835 | tree.Weight = weight;
|
---|
1836 | return tree;
|
---|
1837 | }
|
---|
1838 | private static IEnumerable<ISymbolicExpressionTreeNode> InvertNodes(IEnumerable<ISymbolicExpressionTreeNode> nodes, Func<ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode> invertFunc) {
|
---|
1839 | if (nodes.Count() == 1)
|
---|
1840 | return nodes.Select(invertFunc);
|
---|
1841 | var first = nodes.First().ToEnumerable();
|
---|
1842 | var remaining = nodes.Skip(1).Select(invertFunc);
|
---|
1843 | return first.Concat(remaining);
|
---|
1844 | }
|
---|
1845 |
|
---|
1846 | #endregion
|
---|
1847 | }
|
---|
1848 | }
|
---|