[3425] | 1 | #region License Information
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| 2 | /* HeuristicLab
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| 3 | * Copyright (C) 2002-2010 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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| 4 | *
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| 5 | * This file is part of HeuristicLab.
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| 6 | *
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| 7 | * HeuristicLab is free software: you can redistribute it and/or modify
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| 8 | * it under the terms of the GNU General Public License as published by
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| 9 | * the Free Software Foundation, either version 3 of the License, or
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| 10 | * (at your option) any later version.
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| 11 | *
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| 12 | * HeuristicLab is distributed in the hope that it will be useful,
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| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 15 | * GNU General Public License for more details.
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| 16 | *
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| 17 | * You should have received a copy of the GNU General Public License
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| 18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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| 19 | */
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| 20 | #endregion
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| 21 |
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| 22 | using System;
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| 23 | using System.Collections.Generic;
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| 24 | using System.Linq;
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| 25 | using HeuristicLab.Collections;
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| 26 | using HeuristicLab.Core;
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| 27 | using HeuristicLab.Data;
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| 28 | using HeuristicLab.Parameters;
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| 29 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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| 30 | using HeuristicLab.PluginInfrastructure;
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| 31 |
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| 32 | namespace HeuristicLab.Operators {
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| 33 | /// <summary>
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| 34 | /// Base class for stochastic multi operators.
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| 35 | /// </summary>
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[3527] | 36 | [Item("StochasticMultiOperator<T>", "Base class for stochastic multi operators.")]
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[3425] | 37 | [StorableClass]
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| 38 | public abstract class StochasticMultiOperator<T> : MultiOperator<T> where T : class, IOperator {
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| 39 | /// <summary>
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| 40 | /// Should return true if the StochasticMultiOperator should create a new child operation with the selected successor
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| 41 | /// or if it should create a new operation. If you need to shield the parameters of the successor you should return true here.
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| 42 | /// </summary>
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| 43 | protected abstract bool CreateChildOperation { get; }
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| 44 |
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| 45 | public ValueLookupParameter<DoubleArray> ProbabilitiesParameter {
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| 46 | get { return (ValueLookupParameter<DoubleArray>)Parameters["Probabilities"]; }
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| 47 | }
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| 48 | public ILookupParameter<IRandom> RandomParameter {
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| 49 | get { return (ILookupParameter<IRandom>)Parameters["Random"]; }
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| 50 | }
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| 51 |
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| 52 | public DoubleArray Probabilities {
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| 53 | get { return ProbabilitiesParameter.Value; }
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| 54 | set { ProbabilitiesParameter.Value = value; }
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| 55 | }
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| 56 |
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| 57 | [StorableConstructor]
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| 58 | protected StochasticMultiOperator(bool deserializing) : base(deserializing) { }
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| 59 | /// <summary>
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[3527] | 60 | /// Initializes a new instance of <see cref="StochasticMultiOperator"/> with two parameters
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[3425] | 61 | /// (<c>Probabilities</c> and <c>Random</c>).
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| 62 | /// </summary>
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| 63 | public StochasticMultiOperator()
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| 64 | : base() {
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| 65 | Parameters.Add(new ValueLookupParameter<DoubleArray>("Probabilities", "The array of relative probabilities for each operator.", new DoubleArray()));
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| 66 | Parameters.Add(new LookupParameter<IRandom>("Random", "The random number generator to use."));
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| 67 | }
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| 68 |
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[3445] | 69 | protected override void Operators_ItemsRemoved(object sender, CollectionItemsChangedEventArgs<IndexedItem<T>> e) {
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| 70 | base.Operators_ItemsRemoved(sender, e);
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[3425] | 71 | if (Probabilities != null && Probabilities.Length > Operators.Count) {
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| 72 | List<double> probs = new List<double>(Probabilities.Cast<double>());
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| 73 | var sorted = e.Items.OrderByDescending(x => x.Index);
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| 74 | foreach (IndexedItem<T> item in sorted)
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| 75 | if (probs.Count > item.Index) probs.RemoveAt(item.Index);
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| 76 | Probabilities = new DoubleArray(probs.ToArray());
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| 77 | }
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| 78 | }
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| 79 |
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[3445] | 80 | protected override void Operators_ItemsAdded(object sender, HeuristicLab.Collections.CollectionItemsChangedEventArgs<IndexedItem<T>> e) {
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| 81 | base.Operators_ItemsAdded(sender, e);
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[3425] | 82 | if (Probabilities != null && Probabilities.Length < Operators.Count) {
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| 83 | DoubleArray probs = new DoubleArray(Operators.Count);
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| 84 | double avg = 0;
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| 85 | if (Probabilities.Length > 0) {
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[3445] | 86 | int zeros = 0;
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| 87 | for (int i = 0; i < Probabilities.Length; i++) {
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| 88 | if (Probabilities[i] == 0) zeros++;
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| 89 | else avg += Probabilities[i];
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| 90 | }
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| 91 | if (Probabilities.Length - zeros > 0)
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| 92 | avg /= (double)(Probabilities.Length - zeros);
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| 93 | else avg = 1;
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[3425] | 94 | } else avg = 1;
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| 95 |
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| 96 | var added = e.Items.OrderBy(x => x.Index).ToList();
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| 97 | int insertCount = 0;
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| 98 | for (int i = 0; i < Operators.Count; i++) {
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| 99 | if (insertCount < added.Count && i == added[insertCount].Index) {
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| 100 | probs[i] = avg;
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| 101 | insertCount++;
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| 102 | } else if (i - insertCount < Probabilities.Length) {
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| 103 | probs[i] = Probabilities[i - insertCount];
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| 104 | } else probs[i] = avg;
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| 105 | }
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| 106 | Probabilities = probs;
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| 107 | }
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| 108 | }
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| 109 |
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| 110 | /// <summary>
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| 111 | /// Applies an operator of the branches to the current scope with a
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| 112 | /// specific probability.
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| 113 | /// </summary>
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| 114 | /// <exception cref="InvalidOperationException">Thrown when the list of probabilites does not
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| 115 | /// match the number of operators.</exception>
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| 116 | /// <returns>A new operation with the operator that was selected followed by the current operator's successor.</returns>
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| 117 | public override IOperation Apply() {
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| 118 | IRandom random = RandomParameter.ActualValue;
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| 119 | DoubleArray probabilities = ProbabilitiesParameter.ActualValue;
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| 120 | if(probabilities.Length != Operators.Count) {
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[3527] | 121 | throw new InvalidOperationException(Name + ": The list of probabilities has to match the number of operators");
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[3425] | 122 | }
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| 123 | double sum = 0;
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| 124 | for (int i = 0; i < Operators.Count; i++) {
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| 125 | sum += probabilities[i];
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| 126 | }
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| 127 | double r = random.NextDouble() * sum;
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| 128 | sum = 0;
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| 129 | IOperator successor = null;
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| 130 | for(int i = 0; i < Operators.Count; i++) {
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| 131 | sum += probabilities[i];
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| 132 | if(sum > r) {
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| 133 | successor = Operators[i];
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| 134 | break;
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| 135 | }
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| 136 | }
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| 137 | OperationCollection next = new OperationCollection(base.Apply());
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| 138 | if (successor != null) {
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| 139 | if (CreateChildOperation)
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| 140 | next.Insert(0, ExecutionContext.CreateChildOperation(successor));
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| 141 | else next.Insert(0, ExecutionContext.CreateOperation(successor));
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| 142 | }
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| 143 | return next;
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| 144 | }
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| 145 | }
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| 146 | }
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