[8017] | 1 | #region License Information
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| 2 | /* HeuristicLab
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[12969] | 3 | * Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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[8017] | 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 HeuristicLab.Common;
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| 24 | using HeuristicLab.Core;
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| 25 | using HeuristicLab.Data;
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| 26 | using HeuristicLab.Parameters;
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| 27 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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| 28 |
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| 29 | namespace HeuristicLab.Encodings.IntegerVectorEncoding {
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| 30 | /// <summary>
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| 31 | /// Rounded blend alpha crossover for integer vectors (BLX-a). Creates a new offspring by selecting a random value
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| 32 | /// from the interval between the two alleles of the parent solutions and rounding the result to the next feasible
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| 33 | /// integer. The interval is increased in both directions by the factor alpha.
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| 34 | /// </summary>
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| 35 | [Item("RoundedBlendAlphaCrossover", "The rounded blend alpha crossover (BLX-a) for integer vectors creates new offspring by sampling a new value in the range [min_i - d * alpha, max_i + d * alpha) at each position i and rounding the result to the next feasible integer. Here min_i and max_i are the smaller and larger value of the two parents at position i and d is max_i - min_i.")]
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| 36 | [StorableClass]
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| 37 | public class RoundedBlendAlphaCrossover : BoundedIntegerVectorCrossover {
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| 38 | /// <summary>
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| 39 | /// The alpha parameter specifies how much the interval between the parents should be extended to the left and right.
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| 40 | /// The value of this parameter also determines the name of the operator: BLX-0.0 for example means alpha is set to 0.
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| 41 | /// When Alpha is 0, then the offspring will only be chosen in between the parents, the bigger alpha is the more it will be possible to choose
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| 42 | /// values left and right of the min and max value for each gene.
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| 43 | /// </summary>
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| 44 | public ValueLookupParameter<DoubleValue> AlphaParameter {
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| 45 | get { return (ValueLookupParameter<DoubleValue>)Parameters["Alpha"]; }
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| 46 | }
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| 47 |
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| 48 | [StorableConstructor]
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| 49 | protected RoundedBlendAlphaCrossover(bool deserializing) : base(deserializing) { }
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| 50 | protected RoundedBlendAlphaCrossover(RoundedBlendAlphaCrossover original, Cloner cloner) : base(original, cloner) { }
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| 51 | /// <summary>
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| 52 | /// Initializes a new instance of <see cref="RoundedBlendAlphaCrossover"/> with one parameter (<c>Alpha</c>).
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| 53 | /// </summary>
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| 54 | public RoundedBlendAlphaCrossover()
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| 55 | : base() {
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| 56 | Parameters.Add(new ValueLookupParameter<DoubleValue>("Alpha", "The Alpha parameter controls the extension of the range beyond the two parents. It must be >= 0. A value of 0.5 means that half the range is added to both sides of the intervals.", new DoubleValue(0.5)));
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| 57 | }
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| 58 |
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| 59 | public override IDeepCloneable Clone(Cloner cloner) {
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| 60 | return new RoundedBlendAlphaCrossover(this, cloner);
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| 61 | }
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| 62 |
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| 63 | /// <summary>
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| 64 | /// Performs the rounded blend alpha crossover (BLX-a) of two integer vectors.<br/>
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| 65 | /// It creates new offspring by sampling a new value in the range [min_i - d * alpha, max_i + d * alpha) at each position i
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| 66 | /// and rounding the result to the next integer.
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| 67 | /// Here min_i and max_i are the smaller and larger value of the two parents at position i and d is max_i - min_i.
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| 68 | /// </summary>
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| 69 | /// <exception cref="ArgumentException">
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| 70 | /// Thrown when <paramref name="parent1"/> and <paramref name="parent2"/> are of different length or<br/>
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| 71 | /// when <paramref name="alpha"/> is less than 0.
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| 72 | /// </exception>
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| 73 | /// <param name="random">The random number generator.</param>
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| 74 | /// <param name="parent1">The first parent for the crossover operation.</param>
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| 75 | /// <param name="parent2">The second parent for the crossover operation.</param>
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| 76 | /// <param name="bounds">The bounds and step size for each dimension (will be cycled in case there are less rows than elements in the parent vectors).</param>
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| 77 | /// <param name="alpha">The alpha value for the crossover.</param>
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| 78 | /// <returns>The newly created integer vector resulting from the crossover operation.</returns>
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| 79 | public static IntegerVector Apply(IRandom random, IntegerVector parent1, IntegerVector parent2, IntMatrix bounds, DoubleValue alpha) {
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| 80 | if (parent1.Length != parent2.Length) throw new ArgumentException("RoundedBlendAlphaCrossover: The parents' vectors are of different length.", "parent1");
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| 81 | if (alpha.Value < 0) throw new ArgumentException("RoundedBlendAlphaCrossover: Paramter alpha must be greater or equal than 0.", "alpha");
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| 82 | if (bounds == null || bounds.Rows < 1 || bounds.Columns < 2) throw new ArgumentException("RoundedBlendAlphaCrossover: Invalid bounds specified.", "bounds");
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| 83 |
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| 84 | int length = parent1.Length;
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| 85 | var result = new IntegerVector(length);
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| 86 | double max = 0, min = 0, d = 0, resMin = 0, resMax = 0;
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[8790] | 87 | int minBound, maxBound, step = 1;
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[8017] | 88 |
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| 89 | for (int i = 0; i < length; i++) {
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[8790] | 90 | minBound = bounds[i % bounds.Rows, 0];
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| 91 | maxBound = bounds[i % bounds.Rows, 1];
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[8017] | 92 | if (bounds.Columns > 2) step = bounds[i % bounds.Rows, 2];
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[8790] | 93 | maxBound = FloorFeasible(minBound, maxBound, step, maxBound - 1);
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| 94 |
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[8017] | 95 | max = Math.Max(parent1[i], parent2[i]);
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| 96 | min = Math.Min(parent1[i], parent2[i]);
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| 97 | d = Math.Abs(max - min);
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[8790] | 98 | resMin = FloorFeasible(minBound, maxBound, step, min - d * alpha.Value);
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| 99 | resMax = CeilingFeasible(minBound, maxBound, step, max + d * alpha.Value);
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[8017] | 100 |
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[8790] | 101 | result[i] = RoundFeasible(minBound, maxBound, step, resMin + random.NextDouble() * Math.Abs(resMax - resMin));
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[8017] | 102 | }
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| 103 | return result;
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| 104 | }
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| 105 |
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| 106 | /// <summary>
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| 107 | /// Checks that the number of parents is equal to 2 and forwards the call to <see cref="Apply(IRandom, RealVector, RealVector, DoubleValue)"/>.
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| 108 | /// </summary>
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| 109 | /// <exception cref="ArgumentException">Thrown when the number of parents is not equal to 2.</exception>
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| 110 | /// <exception cref="InvalidOperationException">Thrown when the parameter alpha could not be found.</exception>
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| 111 | /// <param name="random">The random number generator to use.</param>
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| 112 | /// <param name="parents">The collection of parents (must be of size 2).</param>
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| 113 | /// <param name="bounds">The bounds and step size for each dimension (will be cycled in case there are less rows than elements in the parent vectors).</param>
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| 114 | /// <returns>The integer vector resulting from the crossover operation.</returns>
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| 115 | protected override IntegerVector CrossBounded(IRandom random, ItemArray<IntegerVector> parents, IntMatrix bounds) {
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| 116 | if (parents.Length != 2) throw new ArgumentException("RoundedBlendAlphaCrossover: The number of parents is not equal to 2", "parents");
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| 117 | if (AlphaParameter.ActualValue == null) throw new InvalidOperationException("RoundedBlendAlphaCrossover: Parameter " + AlphaParameter.ActualName + " could not be found.");
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| 118 | return Apply(random, parents[0], parents[1], bounds, AlphaParameter.ActualValue);
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| 119 | }
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| 120 | }
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| 121 | }
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