Last change
on this file since 18066 was
15273,
checked in by pkimmesw, 7 years ago
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#2665 Started Plush Encoding, Added Zero Error Individual Count Analyzer
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File size:
945 bytes
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1 | namespace HeuristicLab.Problems.ProgramSynthesis.Base.Extensions {
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2 | using System;
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3 | using System.Collections.Generic;
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4 | using System.Linq;
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5 |
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6 | using HeuristicLab.Core;
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7 | using HeuristicLab.Random;
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8 |
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9 | public static class EnumerableExtensions {
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10 | public static T RandomWeightedOrDefault<T>(this IEnumerable<T> items, IRandom random, Func<T, double> weightResolver) {
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11 | random = random ?? new MersenneTwister();
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12 | var totalWeight = items.Sum(weightResolver);
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13 |
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14 | // The weight we are after...
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15 | var itemWeightIndex = random.NextDouble() * totalWeight;
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16 | var currentWeightIndex = 0d;
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17 |
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18 | foreach (var item in items) {
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19 | currentWeightIndex += weightResolver(item);
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20 |
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21 | // If we've hit or passed the weight we are after for this item then it's the one we want....
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22 | if (currentWeightIndex >= itemWeightIndex)
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23 | return item;
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24 | }
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25 |
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26 | return default(T);
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27 | }
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28 | }
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29 | }
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