source: tags/3.3.0/HeuristicLab.Selection/3.3/OffspringSelector.cs @ 3856

Last change on this file since 3856 was 3856, checked in by abeham, 11 years ago

#1018

  • Added OS fix to 3.3.0.0 tag
File size: 9.0 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2010 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
22using System;
23using System.Collections.Generic;
24using System.Linq;
25using HeuristicLab.Core;
26using HeuristicLab.Data;
27using HeuristicLab.Operators;
28using HeuristicLab.Parameters;
29using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
30
31namespace HeuristicLab.Selection {
32  [Item("OffspringSelector", "Selects among the offspring population those that are designated successful and discards the unsuccessful offspring, except for some lucky losers. It expects the parent scopes to be below the first sub-scope, and offspring scopes to be below the second sub-scope separated again in two sub-scopes, the first with the failed offspring and the second with successful offspring.")]
33  [StorableClass]
34  public class OffspringSelector : SingleSuccessorOperator {
35
36    public ValueLookupParameter<DoubleValue> MaximumSelectionPressureParameter {
37      get { return (ValueLookupParameter<DoubleValue>)Parameters["MaximumSelectionPressure"]; }
38    }
39    public ValueLookupParameter<DoubleValue> SuccessRatioParameter {
40      get { return (ValueLookupParameter<DoubleValue>)Parameters["SuccessRatio"]; }
41    }
42    public LookupParameter<DoubleValue> SelectionPressureParameter {
43      get { return (ValueLookupParameter<DoubleValue>)Parameters["SelectionPressure"]; }
44    }
45    public LookupParameter<DoubleValue> CurrentSuccessRatioParameter {
46      get { return (LookupParameter<DoubleValue>)Parameters["CurrentSuccessRatio"]; }
47    }
48    public LookupParameter<ItemList<IScope>> OffspringPopulationParameter {
49      get { return (LookupParameter<ItemList<IScope>>)Parameters["OffspringPopulation"]; }
50    }
51    public LookupParameter<IntValue> OffspringPopulationWinnersParameter {
52      get { return (LookupParameter<IntValue>)Parameters["OffspringPopulationWinners"]; }
53    }
54    public ScopeTreeLookupParameter<BoolValue> SuccessfulOffspringParameter {
55      get { return (ScopeTreeLookupParameter<BoolValue>)Parameters["SuccessfulOffspring"]; }
56    }
57    public OperatorParameter OffspringCreatorParameter {
58      get { return (OperatorParameter)Parameters["OffspringCreator"]; }
59    }
60
61    public IOperator OffspringCreator {
62      get { return OffspringCreatorParameter.Value; }
63      set { OffspringCreatorParameter.Value = value; }
64    }
65
66    public OffspringSelector()
67      : base() {
68      Parameters.Add(new ValueLookupParameter<DoubleValue>("MaximumSelectionPressure", "The maximum selection pressure which prematurely terminates the offspring selection step."));
69      Parameters.Add(new ValueLookupParameter<DoubleValue>("SuccessRatio", "The ratio of successful offspring that has to be produced."));
70      Parameters.Add(new ValueLookupParameter<DoubleValue>("SelectionPressure", "The amount of selection pressure currently necessary to fulfill the success ratio."));
71      Parameters.Add(new ValueLookupParameter<DoubleValue>("CurrentSuccessRatio", "The current success ratio indicates how much of the successful offspring have already been generated."));
72      Parameters.Add(new LookupParameter<ItemList<IScope>>("OffspringPopulation", "Temporary store of the offspring population."));
73      Parameters.Add(new LookupParameter<IntValue>("OffspringPopulationWinners", "Temporary store the number of successful offspring in the offspring population."));
74      Parameters.Add(new ScopeTreeLookupParameter<BoolValue>("SuccessfulOffspring", "True if the offspring was more successful than its parents.", 2));
75      Parameters.Add(new OperatorParameter("OffspringCreator", "The operator used to create new offspring."));
76    }
77
78    public override IOperation Apply() {
79      double maxSelPress = MaximumSelectionPressureParameter.ActualValue.Value;
80      double successRatio = SuccessRatioParameter.ActualValue.Value;
81      IScope scope = ExecutionContext.Scope;
82      IScope parents = scope.SubScopes[0];
83      IScope offspring = scope.SubScopes[1];
84      int populationSize = parents.SubScopes.Count;
85
86      // retrieve actual selection pressure and success ratio
87      DoubleValue selectionPressure = SelectionPressureParameter.ActualValue;
88      if (selectionPressure == null) {
89        selectionPressure = new DoubleValue(0);
90        SelectionPressureParameter.ActualValue = selectionPressure;
91      }
92      DoubleValue currentSuccessRatio = CurrentSuccessRatioParameter.ActualValue;
93      if (currentSuccessRatio == null) {
94        currentSuccessRatio = new DoubleValue(0);
95        CurrentSuccessRatioParameter.ActualValue = currentSuccessRatio;
96      }
97
98      // retrieve next population
99      ItemList<IScope> population = OffspringPopulationParameter.ActualValue;
100      IntValue successfulOffspring;
101      if (population == null) {
102        population = new ItemList<IScope>();
103        OffspringPopulationParameter.ActualValue = population;
104        selectionPressure.Value = 0; // initialize selection pressure for this round
105        currentSuccessRatio.Value = 0; // initialize current success ratio for this round
106        successfulOffspring = new IntValue(0);
107        OffspringPopulationWinnersParameter.ActualValue = successfulOffspring;
108      } else successfulOffspring = OffspringPopulationWinnersParameter.ActualValue;
109     
110      int worseOffspringNeeded = (int)((1 - successRatio) * populationSize) - (population.Count - successfulOffspring.Value);
111      int successfulOffspringAdded = 0;
112
113      // implement the ActualValue fetch here - otherwise the parent scope would also be included, given that there may be 1000 or more parents, this is quite unnecessary
114      string tname = SuccessfulOffspringParameter.TranslatedName;
115      double tmpSelPress = selectionPressure.Value, tmpSelPressInc = 1.0 / populationSize;
116      for (int i = 0; i < offspring.SubScopes.Count; i++) {
117        // fetch value
118        IVariable tmpVar;
119        if (!offspring.SubScopes[i].Variables.TryGetValue(tname, out tmpVar)) throw new InvalidOperationException(Name + ": Could not determine if an offspring was successful or not.");
120        BoolValue tmp = (tmpVar.Value as BoolValue);
121        if (tmp == null) throw new InvalidOperationException(Name + ": The variable that indicates whether an offspring is successful or not must contain a BoolValue.");
122
123        // add to population
124        if (tmp.Value) {
125          IScope currentOffspring = offspring.SubScopes[i];
126          offspring.SubScopes.Remove(currentOffspring);
127          i--;
128          population.Add(currentOffspring);
129          successfulOffspringAdded++;
130        } else if (worseOffspringNeeded > 0 || tmpSelPress >= maxSelPress) {
131          IScope currentOffspring = offspring.SubScopes[i];
132          offspring.SubScopes.Remove(currentOffspring);
133          i--;
134          population.Add(currentOffspring);
135          worseOffspringNeeded--;
136        }
137        tmpSelPress += tmpSelPressInc;
138        if (population.Count == populationSize) break;
139      }
140      successfulOffspring.Value += successfulOffspringAdded;
141
142      // calculate actual selection pressure and success ratio
143      selectionPressure.Value = tmpSelPress;
144      currentSuccessRatio.Value = successfulOffspring.Value / ((double)populationSize);
145
146      // check if enough children have been generated
147      if (((selectionPressure.Value < maxSelPress) && (currentSuccessRatio.Value < successRatio)) ||
148          (population.Count < populationSize)) {
149        // more children required -> reduce left and start children generation again
150        scope.SubScopes.Remove(parents);
151        scope.SubScopes.Remove(offspring);
152        while(parents.SubScopes.Count > 0)
153          scope.SubScopes.Add(parents.SubScopes[0]);
154
155        IOperator moreOffspring = OffspringCreatorParameter.ActualValue as IOperator;
156        if (moreOffspring == null) throw new InvalidOperationException(Name + ": More offspring are required, but no operator specified for creating them.");
157        return ExecutionContext.CreateOperation(moreOffspring);
158      } else {
159        // enough children generated
160        offspring.SubScopes.Clear();
161        offspring.SubScopes.AddRange(population);
162
163        scope.Variables.Remove(OffspringPopulationParameter.TranslatedName);
164        scope.Variables.Remove(OffspringPopulationWinnersParameter.TranslatedName);
165        return base.Apply();
166      }
167    }
168  }
169}
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