[7476] | 1 | #region License Information
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| 2 | /* HeuristicLab
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[11171] | 3 | * Copyright (C) 2002-2014 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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[7476] | 4 | *
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| 5 | * This file is part of HeuristicLab.
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| 6 | *
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| 7 | * HeuristicLab is free software: you can redistribute it and/or modify
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| 8 | * it under the terms of the GNU General Public License as published by
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| 9 | * the Free Software Foundation, either version 3 of the License, or
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| 10 | * (at your option) any later version.
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| 11 | *
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| 12 | * HeuristicLab is distributed in the hope that it will be useful,
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| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 15 | * GNU General Public License for more details.
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| 16 | *
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| 17 | * You should have received a copy of the GNU General Public License
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| 18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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| 19 | */
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| 20 | #endregion
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| 21 |
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| 22 | using System;
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| 23 | using System.Collections.Generic;
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| 24 | using System.Linq;
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| 25 | using HeuristicLab.Common;
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| 26 | using HeuristicLab.Core;
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[7481] | 27 | using HeuristicLab.Data;
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[7476] | 28 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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| 29 | using HeuristicLab.Parameters;
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[7481] | 30 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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[7476] | 31 |
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| 32 | namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
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[7497] | 33 | [Item("DepthConstrainedCrossover", "An operator which performs subtree swapping within a specific depth range. The range parameter controls the crossover behavior:\n" +
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| 34 | "- HighLevel (upper 25% of the tree)\n" +
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| 35 | "- Standard (mid 50% of the tree)\n" +
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| 36 | "- LowLevel (lower 25% of the tree)")]
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[7476] | 37 | public sealed class SymbolicDataAnalysisExpressionDepthConstrainedCrossover<T> :
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| 38 | SymbolicDataAnalysisExpressionCrossover<T> where T : class, IDataAnalysisProblemData {
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| 39 | private enum Ranges { HighLevel, Standard, LowLevel };
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| 40 | private const string DepthRangeParameterName = "DepthRange";
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[7489] | 41 |
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[7476] | 42 | #region Parameter properties
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[8203] | 43 | public IConstrainedValueParameter<StringValue> DepthRangeParameter {
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| 44 | get { return (IConstrainedValueParameter<StringValue>)Parameters[DepthRangeParameterName]; }
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[7476] | 45 | }
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| 46 | #endregion
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| 47 |
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| 48 | #region Properties
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| 49 | public StringValue DepthRange {
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| 50 | get { return (StringValue)DepthRangeParameter.ActualValue; }
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| 51 | }
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| 52 | #endregion
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| 53 |
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| 54 | [StorableConstructor]
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| 55 | private SymbolicDataAnalysisExpressionDepthConstrainedCrossover(bool deserializing) : base(deserializing) { }
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| 56 | private SymbolicDataAnalysisExpressionDepthConstrainedCrossover(SymbolicDataAnalysisExpressionCrossover<T> original, Cloner cloner)
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| 57 | : base(original, cloner) { }
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| 58 | public SymbolicDataAnalysisExpressionDepthConstrainedCrossover()
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| 59 | : base() {
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| 60 | Parameters.Add(new ConstrainedValueParameter<StringValue>(DepthRangeParameterName, "Depth range specifier"));
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[7490] | 61 | DepthRangeParameter.ValidValues.Add(new StringValue(Enum.GetName(typeof(Ranges), Ranges.HighLevel)).AsReadOnly());
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| 62 | DepthRangeParameter.ValidValues.Add(new StringValue(Enum.GetName(typeof(Ranges), Ranges.Standard)).AsReadOnly());
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| 63 | DepthRangeParameter.ValidValues.Add(new StringValue(Enum.GetName(typeof(Ranges), Ranges.LowLevel)).AsReadOnly());
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[7521] | 64 | name = "DepthConstrainedCrossover";
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[7476] | 65 | }
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| 66 | public override IDeepCloneable Clone(Cloner cloner) { return new SymbolicDataAnalysisExpressionDepthConstrainedCrossover<T>(this, cloner); }
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| 67 |
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[7481] | 68 | public override ISymbolicExpressionTree Crossover(IRandom random, ISymbolicExpressionTree parent0, ISymbolicExpressionTree parent1) {
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[7476] | 69 | return Cross(random, parent0, parent1, MaximumSymbolicExpressionTreeDepth.Value, MaximumSymbolicExpressionTreeLength.Value, DepthRange.Value);
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| 70 | }
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| 71 |
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| 72 |
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| 73 | /// <summary>
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| 74 | /// Takes two parent individuals P0 and P1.
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| 75 | /// Randomly choose nodes that fall within the specified depth range in both parents.
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| 76 | /// </summary>
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| 77 | /// <param name="random">Pseudo-random number generator.</param>
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| 78 | /// <param name="parent0">First parent.</param>
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| 79 | /// <param name="parent1">Second parent.</param>
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| 80 | /// <param name="maxDepth">Maximum allowed length depth.</param>
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| 81 | /// <param name="maxLength">Maximum allowed tree length.</param>
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| 82 | /// <param name="mode">Controls the crossover behavior:
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| 83 | /// - HighLevel (upper 25% of the tree),
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| 84 | /// - Standard (mid 50%)
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| 85 | /// - LowLevel (low 25%)</param>
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| 86 | /// <returns></returns>
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| 87 | public static ISymbolicExpressionTree Cross(IRandom random, ISymbolicExpressionTree parent0, ISymbolicExpressionTree parent1, int maxDepth, int maxLength, string mode) {
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[7497] | 88 | int depth = parent0.Root.GetDepth() - 1; // substract 1 because the tree levels are counted from 0
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[7476] | 89 | var depthRange = new IntRange();
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| 90 | const int depthOffset = 2; // skip the first 2 levels (root + startNode)
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[8203] | 91 | switch ((Ranges)Enum.Parse(typeof(Ranges), mode)) {
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| 92 | case Ranges.HighLevel:
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[7476] | 93 | depthRange.Start = depthOffset; // skip the first 2 levels (root + startNode)
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| 94 | depthRange.End = depthRange.Start + (int)Math.Round(depth * 0.25);
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| 95 | break;
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[8203] | 96 | case Ranges.Standard:
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[7476] | 97 | depthRange.Start = depthOffset + (int)Math.Round(depth * 0.25);
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| 98 | depthRange.End = depthRange.Start + (int)Math.Round(depth * 0.5);
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| 99 | break;
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[8203] | 100 | case Ranges.LowLevel:
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[7476] | 101 | depthRange.Start = depthOffset + (int)Math.Round(depth * 0.75);
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| 102 | depthRange.End = Math.Max(depthRange.Start, depth);
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| 103 | break;
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| 104 | }
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| 105 |
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| 106 | // make sure that the depth range does not exceeded the actual depth of parent0
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| 107 | if (depthRange.Start > depth)
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| 108 | depthRange.Start = depth;
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| 109 | if (depthRange.End < depthRange.Start)
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| 110 | depthRange.End = depthRange.Start;
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| 111 |
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[7489] | 112 | var crossoverPoints0 = (from node in GetNodesAtDepth(parent0, depthRange) select new CutPoint(node.Parent, node)).ToList();
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[7476] | 113 |
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| 114 | if (crossoverPoints0.Count == 0)
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| 115 | throw new Exception("No crossover points available in the first parent");
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| 116 |
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| 117 | var crossoverPoint0 = crossoverPoints0.SelectRandom(random);
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| 118 |
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| 119 | int level = parent0.Root.GetBranchLevel(crossoverPoint0.Child);
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| 120 | int length = parent0.Root.GetLength() - crossoverPoint0.Child.GetLength();
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| 121 |
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[7489] | 122 | var allowedBranches = (from s in GetNodesAtDepth(parent1, depthRange)
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[7497] | 123 | where s.GetDepth() + level <= maxDepth
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| 124 | where s.GetLength() + length <= maxLength
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| 125 | where crossoverPoint0.IsMatchingPointType(s)
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[7476] | 126 | select s).ToList();
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| 127 | if (allowedBranches.Count == 0) return parent0;
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| 128 | var selectedBranch = allowedBranches.SelectRandom(random);
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[7497] | 129 | Swap(crossoverPoint0, selectedBranch);
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[7476] | 130 | return parent0;
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| 131 | }
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| 132 |
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[7489] | 133 | private static IEnumerable<ISymbolicExpressionTreeNode> GetNodesAtDepth(ISymbolicExpressionTree tree, IntRange depthRange) {
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| 134 | var treeDepth = tree.Root.GetDepth();
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| 135 | return from node in tree.Root.IterateNodesPostfix()
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| 136 | let depth = treeDepth - node.GetDepth()
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| 137 | where depthRange.Start <= depth
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| 138 | where depth <= depthRange.End
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| 139 | select node;
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[7476] | 140 | }
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| 141 | }
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| 142 | }
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