HeuristicLab.Optimization.Operators/3.3/GeneralizedExponentialDiscreteDoubleValueModifier.cs

   1 #region License Information
   2 /* HeuristicLab
   3  * Copyright (C) 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.
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  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 HeuristicLab.Common;
  24 using HeuristicLab.Core;
  25 using HeuristicLab.Data;
  26 using HeuristicLab.Parameters;
  27 using HEAL.Attic;
  28
  29 namespace HeuristicLab.Optimization.Operators {
  30
  31   /// <summary>
  32   /// Modifies a value by exponentially.
  33   /// </summary>
  34   [Item("GeneralizedExponentialDiscreteDoubleValueModifier", @"Modifies the value exponentially.
  35 The base is a standardized exponential function with exponent `Base`
  36 that is then transformed to pass through the startValue at the startIndex
  37 and through the endValue at the endIndex.
  38 For a slow change initially use a value > 1 for `Base`.
  39 For a steep change initially use a value < 1 for `Base`.
  40 Negative slopes are automatically generated if the start value is greater than the end value.
  41 If you use `base`=1 you will get a linear interpolation.")]
  42   [StorableType("349D17F2-44D8-46EB-813F-E6D6E73B007F")]
  43   public class GeneralizedExponentialDiscreteDoubleValueModifier : DiscreteDoubleValueModifier {
  44
  45     protected ValueLookupParameter<DoubleValue> BaseParameter {
  46       get { return (ValueLookupParameter<DoubleValue>) Parameters["Base"]; }
  47     }
  48     private double Base { get { return BaseParameter.Value.Value; } }
  49
  50     [StorableConstructor]
  51     protected GeneralizedExponentialDiscreteDoubleValueModifier(StorableConstructorFlag _) : base(_) { }
  52     protected GeneralizedExponentialDiscreteDoubleValueModifier(GeneralizedExponentialDiscreteDoubleValueModifier original, Cloner cloner) : base(original, cloner) { }
  53     public GeneralizedExponentialDiscreteDoubleValueModifier() {
  54       Parameters.Add(new ValueLookupParameter<DoubleValue>("Base", "Base of the exponential function. Must be > 0. If > 1 steep in the end, if < 1 steep at the start, if == 1 linear interpolation.", new DoubleValue(0.00001)));
  55     }
  56     public override IDeepCloneable Clone(Cloner cloner) {
  57       return new GeneralizedExponentialDiscreteDoubleValueModifier(this, cloner);
  58     }
  59
  60     protected override double Modify(double value, double startValue, double endValue, int index, int startIndex, int endIndex) {
  61       return Apply(value, startValue, endValue, index, startIndex, endIndex, Base);
  62     }
  63
  64     /// <summary>
  65     /// Calculates a new value based on exponential decay or growth.
  66     /// </summary>
  67     /// <exception cref="ArgumentException">Thrown if Base &lt;= 0.</exception>
  68     /// <param name="value">The previous value.</param>
  69     /// <param name="startValue">The initial value.</param>
  70     /// <param name="endValue">The final value.</param>
  71     /// <param name="index">The current index.</param>
  72     /// <param name="startIndex">The initial index.</param>
  73     /// <param name="endIndex">The final index.</param>
  74     /// <returns>The new value.</returns>
  75     public static double Apply(double value, double startValue, double endValue, int index, int startIndex, int endIndex, double @base) {
  76       if (@base <= 0)
  77         throw new ArgumentException("Base must be > 0.");
  78       if (@base == 1.0)
  79         return startValue + (endValue - startValue) * (index - startIndex) / (endIndex - startIndex);
  80       return startValue + (endValue - startValue) * (Math.Pow(@base, 1.0 * (index - startIndex) / (endIndex - startIndex)) - 1) / (@base - 1);
  81     }
  82   }
  83 }