1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2014 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.Common;
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26 | using HeuristicLab.Random;
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27 |
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28 | namespace HeuristicLab.Problems.Instances.DataAnalysis {
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29 | public static class ValueGenerator {
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30 | private static FastRandom rand = new FastRandom();
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31 |
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32 | /// <summary>
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33 | /// Generates a sequence of evenly spaced points between start and end (inclusive!).
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34 | /// </summary>
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35 | /// <param name="start">The smallest and first value of the sequence.</param>
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36 | /// <param name="end">The largest and last value of the sequence.</param>
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37 | /// <param name="stepWidth">The step size between subsequent values.</param>
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38 | /// <returns>An sequence of values from start to end (inclusive)</returns>
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39 | public static IEnumerable<double> GenerateSteps(double start, double end, double stepWidth) {
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40 | if (stepWidth.IsAlmost(0))
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41 | throw new ArgumentException("The step width cannot be zero.");
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42 | if (start < end && stepWidth < 0)
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43 | throw new ArgumentException("The step width must be larger than zero for increasing sequences (start < end).");
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44 | if (start > end && stepWidth > 0)
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45 | throw new ArgumentException("The step width must be smaller than zero for decreasing sequences (start > end).");
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46 | double x = start;
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47 | // x<=end could skip the last value because of numerical problems
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48 | while (x < end || x.IsAlmost(end)) {
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49 | yield return x;
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50 | x += stepWidth;
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51 | }
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52 | }
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53 |
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54 | /// <summary>
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55 | /// Generate a logarithmic sequence between start and end by applying a power-of-10 function to an underlying evenly spaced sequence
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56 | /// </summary>
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57 | /// <param name="start">The start of the sequence</param>
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58 | /// <param name="end">The end of the sequence</param>
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59 | /// <param name="stepWidth">The stepwidth for the original sequence before the points are transformed</param>
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60 | /// <returns>A logarithmic sequence from start to end (inclusive)</returns>
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61 | public static IEnumerable<double> GenerateLogarithmicSteps(double start, double end, double stepWidth) {
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62 | return GenerateSteps(start, end, stepWidth, x => Math.Pow(10, x));
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63 | }
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64 |
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65 | /// <summary>
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66 | /// Generates a sequence of points between start and end according to given transformation
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67 | /// </summary>
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68 | /// <param name="start">The smallest and first value of the sequence.</param>
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69 | /// <param name="end">The largest and last value of the sequence.</param>
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70 | /// <param name="stepWidth">The step size between subsequent values (before transform)</param>
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71 | /// <param name="transform">The transform function</param>
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72 | /// <returns></returns>
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73 | public static IEnumerable<double> GenerateSteps(double start, double end, double stepWidth, Func<double, double> transform) {
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74 | return GenerateSteps(start, end, stepWidth).Select(transform);
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75 | }
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76 |
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77 | /// <summary>
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78 | /// Generates uniformly distributed values between start and end (inclusive!)
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79 | /// </summary>
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80 | /// <param name="n">Number of values to generate.</param>
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81 | /// <param name="start">The lower value (inclusive)</param>
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82 | /// <param name="end">The upper value (inclusive)</param>
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83 | /// <returns>An enumerable including n values in [start, end]</returns>
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84 | public static IEnumerable<double> GenerateUniformDistributedValues(int n, double start, double end) {
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85 | for (int i = 0; i < n; i++) {
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86 | // we need to return a random value including end.
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87 | // so we cannot use rand.NextDouble() as it returns a value strictly smaller than 1.
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88 | double r = rand.NextUInt() / (double)uint.MaxValue; // r \in [0,1]
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89 | yield return r * (end - start) + start;
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90 | }
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91 | }
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92 |
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93 | /// <summary>
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94 | /// Generates normally distributed values sampling from N(mu, sigma)
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95 | /// </summary>
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96 | /// <param name="n">Number of values to generate.</param>
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97 | /// <param name="mu">The mu parameter of the normal distribution</param>
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98 | /// <param name="sigma">The sigma parameter of the normal distribution</param>
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99 | /// <returns>An enumerable including n values ~ N(mu, sigma)</returns>
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100 | public static IEnumerable<double> GenerateNormalDistributedValues(int n, double mu, double sigma) {
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101 | for (int i = 0; i < n; i++)
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102 | yield return NormalDistributedRandom.NextDouble(rand, mu, sigma);
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103 | }
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104 |
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105 | // iterative approach
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106 | public static IEnumerable<IEnumerable<double>> GenerateAllCombinationsOfValuesInLists(List<List<double>> lists) {
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107 | List<List<double>> allCombinations = new List<List<double>>();
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108 | if (lists.Count < 1) {
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109 | return allCombinations;
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110 | }
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111 |
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112 | List<IEnumerator<double>> enumerators = new List<IEnumerator<double>>();
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113 | foreach (var list in lists) {
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114 | allCombinations.Add(new List<double>());
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115 | enumerators.Add(list.GetEnumerator());
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116 | }
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117 |
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118 | bool finished = !enumerators.All(x => x.MoveNext());
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119 |
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120 | while (!finished) {
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121 | GetCurrentCombination(enumerators, allCombinations);
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122 | finished = MoveNext(enumerators, lists);
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123 | }
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124 | return allCombinations;
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125 | }
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126 |
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127 | private static bool MoveNext(List<IEnumerator<double>> enumerators, List<List<double>> lists) {
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128 | int cur = enumerators.Count - 1;
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129 | while (cur >= 0 && !enumerators[cur].MoveNext()) {
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130 | enumerators[cur] = lists[cur].GetEnumerator();
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131 | enumerators[cur].MoveNext();
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132 | cur--;
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133 | }
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134 | return cur < 0;
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135 | }
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136 |
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137 | private static void GetCurrentCombination(List<IEnumerator<double>> enumerators, List<List<double>> allCombinations) {
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138 | for (int i = 0; i < enumerators.Count(); i++) {
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139 | allCombinations[i].Add(enumerators[i].Current);
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140 | }
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141 | }
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142 | }
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143 | }
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