1 | using System;
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2 | using System.Collections.Generic;
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3 | using System.Linq;
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4 | using HeuristicLab.Common;
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5 | using HeuristicLab.Core;
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6 | using HeuristicLab.Data;
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7 | using HeuristicLab.Parameters;
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8 | using HeuristicLab.Persistence;
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9 |
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10 | namespace HeuristicLab.Problems.DataAnalysis {
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11 | [StorableType("d03d3083-30af-4eb2-845f-fcd1f608875b")]
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12 | [Item("Logarithmic Transformation", "f(x) = log(x, b) | Represents a logarithmic transformation.")]
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13 | public class LogarithmicTransformation : Transformation<double> {
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14 | protected const string BaseParameterName = "Base";
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15 |
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16 | #region Parameters
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17 | public IValueParameter<DoubleValue> BaseParameter {
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18 | get { return (IValueParameter<DoubleValue>)Parameters[BaseParameterName]; }
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19 | }
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20 | #endregion
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21 |
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22 | #region properties
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23 | public override string ShortName {
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24 | get { return "Log"; }
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25 | }
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26 | public double Base {
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27 | get { return BaseParameter.Value.Value; }
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28 | }
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29 | #endregion
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30 |
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31 | [StorableConstructor]
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32 | protected LogarithmicTransformation(StorableConstructorFlag deserializing) : base(deserializing) { }
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33 | protected LogarithmicTransformation(LogarithmicTransformation original, Cloner cloner)
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34 | : base(original, cloner) {
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35 | }
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36 | public LogarithmicTransformation(IEnumerable<string> allowedColumns)
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37 | : base(allowedColumns) {
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38 | Parameters.Add(new ValueParameter<DoubleValue>(BaseParameterName, "b | Base of log-function", new DoubleValue(Math.E)));
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39 | }
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40 |
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41 | public override IDeepCloneable Clone(Cloner cloner) {
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42 | return new LogarithmicTransformation(this, cloner);
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43 | }
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44 |
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45 | public override IEnumerable<double> Apply(IEnumerable<double> data) {
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46 | var b = Base;
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47 | return data.Select(d => d > 0.0 ? Math.Log(d, b) : d);
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48 | }
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49 |
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50 | public override bool Check(IEnumerable<double> data, out string errorMsg) {
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51 | errorMsg = null;
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52 | int errorCounter = data.Count(i => i <= 0.0);
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53 | if (errorCounter > 0) {
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54 | errorMsg = String.Format("{0} values are zero or below zero. Logarithm can not be applied onto these values", errorCounter);
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55 | return false;
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56 | }
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57 | return true;
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58 | }
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59 |
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60 | }
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61 | }
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