[6887] | 1 | #region License Information
|
---|
| 2 | /* HeuristicLab
|
---|
| 3 | * Copyright (C) 2002-2011 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
|
---|
| 4 | *
|
---|
| 5 | * This file is part of HeuristicLab.
|
---|
| 6 | *
|
---|
| 7 | * HeuristicLab is free software: you can redistribute it and/or modify
|
---|
| 8 | * it under the terms of the GNU General Public License as published by
|
---|
| 9 | * the Free Software Foundation, either version 3 of the License, or
|
---|
| 10 | * (at your option) any later version.
|
---|
| 11 | *
|
---|
| 12 | * HeuristicLab is distributed in the hope that it will be useful,
|
---|
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
|
---|
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
---|
| 15 | * GNU General Public License for more details.
|
---|
| 16 | *
|
---|
| 17 | * You should have received a copy of the GNU General Public License
|
---|
| 18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
|
---|
| 19 | */
|
---|
| 20 | #endregion
|
---|
| 21 |
|
---|
| 22 | using System;
|
---|
| 23 | using System.Collections.Generic;
|
---|
| 24 | using System.ComponentModel;
|
---|
| 25 | using System.Linq;
|
---|
| 26 | using HeuristicLab.Common;
|
---|
| 27 | using HeuristicLab.Core;
|
---|
| 28 | using HeuristicLab.Data;
|
---|
| 29 | using HeuristicLab.Parameters;
|
---|
| 30 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
|
---|
| 31 |
|
---|
| 32 | namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding {
|
---|
| 33 | [StorableClass]
|
---|
| 34 | [Item("GrowTreeCreator", "An operator that creates new symbolic expression trees using the 'Grow' method")]
|
---|
| 35 | public class GrowTreeCreator : SymbolicExpressionTreeCreator,
|
---|
| 36 | ISymbolicExpressionTreeSizeConstraintOperator,
|
---|
| 37 | ISymbolicExpressionTreeGrammarBasedOperator {
|
---|
| 38 | private const string MaximumSymbolicExpressionTreeLengthParameterName = "MaximumSymbolicExpressionTreeLength";
|
---|
| 39 | private const string MaximumSymbolicExpressionTreeDepthParameterName = "MaximumSymbolicExpressionTreeDepth";
|
---|
| 40 | private const string SymbolicExpressionTreeGrammarParameterName = "SymbolicExpressionTreeGrammar";
|
---|
| 41 | private const string ClonedSymbolicExpressionTreeGrammarParameterName = "ClonedSymbolicExpressionTreeGrammar";
|
---|
| 42 |
|
---|
| 43 | #region Parameter Properties
|
---|
| 44 | public IValueLookupParameter<IntValue> MaximumSymbolicExpressionTreeLengthParameter {
|
---|
| 45 | get { return (IValueLookupParameter<IntValue>)Parameters[MaximumSymbolicExpressionTreeLengthParameterName]; }
|
---|
| 46 | }
|
---|
| 47 |
|
---|
| 48 | public IValueLookupParameter<IntValue> MaximumSymbolicExpressionTreeDepthParameter {
|
---|
| 49 | get { return (IValueLookupParameter<IntValue>)Parameters[MaximumSymbolicExpressionTreeDepthParameterName]; }
|
---|
| 50 | }
|
---|
| 51 |
|
---|
| 52 | public IValueLookupParameter<ISymbolicExpressionGrammar> SymbolicExpressionTreeGrammarParameter {
|
---|
| 53 | get { return (IValueLookupParameter<ISymbolicExpressionGrammar>)Parameters[SymbolicExpressionTreeGrammarParameterName]; }
|
---|
| 54 | }
|
---|
| 55 |
|
---|
| 56 | public ILookupParameter<ISymbolicExpressionGrammar> ClonedSymbolicExpressionTreeGrammarParameter {
|
---|
[6888] | 57 | get { return (ILookupParameter<ISymbolicExpressionGrammar>)Parameters[ClonedSymbolicExpressionTreeGrammarParameterName]; }
|
---|
[6887] | 58 | }
|
---|
| 59 |
|
---|
| 60 | #endregion
|
---|
| 61 | #region Properties
|
---|
| 62 | public IntValue MaximumSymbolicExpressionTreeDepth {
|
---|
| 63 | get { return MaximumSymbolicExpressionTreeDepthParameter.ActualValue; }
|
---|
| 64 | }
|
---|
| 65 |
|
---|
| 66 | public ISymbolicExpressionGrammar SymbolicExpressionTreeGrammar {
|
---|
| 67 | get { return ClonedSymbolicExpressionTreeGrammarParameter.ActualValue; }
|
---|
| 68 | }
|
---|
| 69 |
|
---|
| 70 | #endregion
|
---|
| 71 |
|
---|
| 72 | [StorableConstructor]
|
---|
| 73 | protected GrowTreeCreator(bool deserializing) : base(deserializing) { }
|
---|
| 74 | protected GrowTreeCreator(GrowTreeCreator original, Cloner cloner) : base(original, cloner) { }
|
---|
| 75 |
|
---|
| 76 | public GrowTreeCreator()
|
---|
| 77 | : base() {
|
---|
| 78 | Parameters.Add(new ValueLookupParameter<IntValue>(MaximumSymbolicExpressionTreeLengthParameterName, "The maximal length (number of nodes) of the symbolic expression tree."));
|
---|
| 79 | Parameters.Add(new ValueLookupParameter<IntValue>(MaximumSymbolicExpressionTreeDepthParameterName, "The maximal depth of the symbolic expression tree (a tree with one node has depth = 0)."));
|
---|
| 80 | Parameters.Add(new ValueLookupParameter<ISymbolicExpressionGrammar>(SymbolicExpressionTreeGrammarParameterName, "The tree grammar that defines the correct syntax of symbolic expression trees that should be created."));
|
---|
| 81 | Parameters.Add(new LookupParameter<ISymbolicExpressionGrammar>(ClonedSymbolicExpressionTreeGrammarParameterName, "An immutable clone of the concrete grammar that is actually used to create and manipulate trees."));
|
---|
| 82 | }
|
---|
| 83 |
|
---|
| 84 | public override IDeepCloneable Clone(Cloner cloner) {
|
---|
| 85 | return new GrowTreeCreator(this, cloner);
|
---|
| 86 | }
|
---|
| 87 |
|
---|
| 88 | public override IOperation Apply() {
|
---|
| 89 | if (ClonedSymbolicExpressionTreeGrammarParameter.ActualValue == null) {
|
---|
| 90 | SymbolicExpressionTreeGrammarParameter.ActualValue.ReadOnly = true;
|
---|
| 91 | IScope globalScope = ExecutionContext.Scope;
|
---|
| 92 | while (globalScope.Parent != null)
|
---|
| 93 | globalScope = globalScope.Parent;
|
---|
| 94 |
|
---|
| 95 | globalScope.Variables.Add(new Variable(ClonedSymbolicExpressionTreeGrammarParameterName, (ISymbolicExpressionGrammar)SymbolicExpressionTreeGrammarParameter.ActualValue.Clone()));
|
---|
| 96 | }
|
---|
| 97 | return base.Apply();
|
---|
| 98 | }
|
---|
| 99 |
|
---|
| 100 | protected override ISymbolicExpressionTree Create(IRandom random) {
|
---|
| 101 | return Create(random, SymbolicExpressionTreeGrammar, MaximumSymbolicExpressionTreeDepth.Value);
|
---|
| 102 | }
|
---|
| 103 |
|
---|
| 104 | /// <summary>
|
---|
| 105 | /// Create a symbolic expression tree using the 'Grow' method.
|
---|
| 106 | /// All symbols are allowed for nodes, so the resulting trees can be of any shape and size.
|
---|
| 107 | /// </summary>
|
---|
| 108 | /// <param name="random">Random generator</param>
|
---|
| 109 | /// <param name="grammar">Available tree grammar</param>
|
---|
| 110 | /// <param name="maxTreeDepth">Maximum tree depth</param>
|
---|
| 111 | /// <returns></returns>
|
---|
| 112 | public static ISymbolicExpressionTree Create(IRandom random, ISymbolicExpressionGrammar grammar, int maxTreeDepth) {
|
---|
| 113 | var tree = new SymbolicExpressionTree();
|
---|
| 114 | var rootNode = (SymbolicExpressionTreeTopLevelNode)grammar.ProgramRootSymbol.CreateTreeNode();
|
---|
| 115 | rootNode.SetGrammar(new SymbolicExpressionTreeGrammar(grammar));
|
---|
| 116 | if (rootNode.HasLocalParameters) rootNode.ResetLocalParameters(random);
|
---|
| 117 |
|
---|
| 118 | var startNode = (SymbolicExpressionTreeTopLevelNode)grammar.StartSymbol.CreateTreeNode();
|
---|
| 119 | startNode.SetGrammar(new SymbolicExpressionTreeGrammar(grammar));
|
---|
| 120 | if (startNode.HasLocalParameters) startNode.ResetLocalParameters(random);
|
---|
| 121 |
|
---|
| 122 | rootNode.AddSubtree(startNode);
|
---|
| 123 |
|
---|
| 124 | Grow(random, startNode, maxTreeDepth - 2);
|
---|
| 125 | tree.Root = rootNode;
|
---|
| 126 | return tree;
|
---|
| 127 | }
|
---|
| 128 |
|
---|
| 129 | public static void Grow(IRandom random, ISymbolicExpressionTreeNode seedNode, int maxDepth) {
|
---|
| 130 | // make sure it is possible to create a trees smaller than maxDepth
|
---|
| 131 | if (seedNode.Grammar.GetMinimumExpressionDepth(seedNode.Symbol) > maxDepth)
|
---|
| 132 | throw new ArgumentException("Cannot create trees of depth " + maxDepth + " or smaller because of grammar constraints.", "maxDepth");
|
---|
| 133 |
|
---|
| 134 | var arity = SampleArity(random, seedNode);
|
---|
[6888] | 135 | // throw an exception if the seedNode happens to be a terminal, since in this case we cannot grow a tree
|
---|
| 136 | if (arity <= 0)
|
---|
| 137 | throw new ArgumentException("Cannot grow tree. Seed node shouldn't have arity zero.");
|
---|
[6887] | 138 |
|
---|
| 139 | var possibleSymbols = seedNode.Grammar.GetAllowedChildSymbols(seedNode.Symbol).Where(s => s.InitialFrequency > 0.0).ToList();
|
---|
| 140 |
|
---|
| 141 | for (var i = 0; i != arity; ++i) {
|
---|
| 142 | var selectedSymbol = possibleSymbols.SelectRandom(random);
|
---|
| 143 | var tree = selectedSymbol.CreateTreeNode();
|
---|
| 144 | if (tree.HasLocalParameters) tree.ResetLocalParameters(random);
|
---|
| 145 | seedNode.AddSubtree(tree);
|
---|
| 146 | }
|
---|
| 147 |
|
---|
[6888] | 148 | // Only iterate over the non-terminal nodes (those which have arity > 0)
|
---|
| 149 | // Start from depth 2 since the first two levels are formed by the rootNode and the seedNode
|
---|
| 150 | foreach (var subTree in seedNode.Subtrees.Where(subTree => subTree.Grammar.GetMaximumSubtreeCount(subTree.Symbol) != 0))
|
---|
| 151 | RecursiveGrow(random, subTree, 2, maxDepth);
|
---|
[6887] | 152 | }
|
---|
| 153 |
|
---|
| 154 | public static void RecursiveGrow(IRandom random, ISymbolicExpressionTreeNode root, int currentDepth, int maxDepth) {
|
---|
| 155 | var arity = SampleArity(random, root);
|
---|
[6888] | 156 | if (arity <= 0)
|
---|
| 157 | throw new ArgumentException("Cannot grow node of arity zero. Expected a function node.");
|
---|
[6887] | 158 |
|
---|
| 159 | var possibleSymbols = currentDepth < maxDepth ?
|
---|
| 160 | root.Grammar.GetAllowedChildSymbols(root.Symbol).Where(s => s.InitialFrequency > 0.0).ToList() :
|
---|
| 161 | root.Grammar.GetAllowedChildSymbols(root.Symbol).Where(s => s.InitialFrequency > 0.0 && root.Grammar.GetMaximumSubtreeCount(s) == 0).ToList();
|
---|
| 162 |
|
---|
| 163 | for (var i = 0; i != arity; ++i) {
|
---|
| 164 | var selectedSymbol = possibleSymbols.SelectRandom(random);
|
---|
| 165 | var tree = selectedSymbol.CreateTreeNode();
|
---|
| 166 | if (tree.HasLocalParameters) tree.ResetLocalParameters(random);
|
---|
| 167 | root.AddSubtree(tree);
|
---|
| 168 | }
|
---|
| 169 |
|
---|
[6888] | 170 | foreach (var subTree in root.Subtrees.Where(subTree => subTree.Grammar.GetMaximumSubtreeCount(subTree.Symbol) != 0))
|
---|
[6887] | 171 | RecursiveGrow(random, subTree, currentDepth + 1, maxDepth);
|
---|
| 172 | }
|
---|
| 173 |
|
---|
| 174 | private static int SampleArity(IRandom random, ISymbolicExpressionTreeNode node) {
|
---|
| 175 | var minArity = node.Grammar.GetMinimumSubtreeCount(node.Symbol);
|
---|
| 176 | var maxArity = node.Grammar.GetMaximumSubtreeCount(node.Symbol);
|
---|
| 177 |
|
---|
| 178 | return random.Next(minArity, maxArity + 1);
|
---|
| 179 | }
|
---|
| 180 | }
|
---|
| 181 | } |
---|