source: branches/2847_M5Regression/HeuristicLab.Algorithms.DataAnalysis/3.4/M5Regression/Spliting/CorrelationSplitter.cs @ 16847

Last change on this file since 16847 was 16847, checked in by gkronber, 4 months ago

#2847: made some minor changes while reviewing

File size: 3.7 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2017 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.
11 *
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
22using System.Collections.Generic;
23using HeuristicLab.Common;
24using HeuristicLab.Core;
25using HeuristicLab.Data;
26using HeuristicLab.Parameters;
27using HEAL.Attic;
28
29namespace HeuristicLab.Algorithms.DataAnalysis {
30  [StorableType("EC3A5009-EE84-4E1A-A537-20F6F1224842")]
31  [Item("CorrelationSplitter", "An experimental split selector that uses correlation coefficients")]
32  public class CorrelationSplitter : SplitterBase {
33    public const string OrderParameterName = "Order";
34    public IFixedValueParameter<DoubleValue> OrderParameter {
35      get { return (IFixedValueParameter<DoubleValue>)Parameters[OrderParameterName]; }
36    }
37    public double Order {
38      get { return OrderParameter.Value.Value; }
39      set { OrderParameter.Value.Value = value; }
40    }
41
42    #region Constructors & Cloning
43    [StorableConstructor]
44    private CorrelationSplitter(StorableConstructorFlag _) { }
45    private CorrelationSplitter(CorrelationSplitter original, Cloner cloner) : base(original, cloner) { }
46    public CorrelationSplitter() {
47      Parameters.Add(new FixedValueParameter<DoubleValue>(OrderParameterName, "The exponent in the split calculation ssrLeft^(1/Order)+ssrRight^(1/Order) (default=1.0).", new DoubleValue(1)));
48    }
49    public override IDeepCloneable Clone(Cloner cloner) {
50      return new CorrelationSplitter(this, cloner);
51    }
52    #endregion
53
54    #region ISplitType
55    protected override void AttributeSplit(IReadOnlyList<double> attValues, IReadOnlyList<double> targetValues, int minLeafSize, out int leftSize, out double maxImpurity, out double splitValue) {
56      leftSize = -1;
57      splitValue = double.MinValue;
58      maxImpurity = double.NegativeInfinity;
59      var splitValues = new List<double>();
60      var splitSizes = new List<int>();
61      var length = attValues.Count;
62
63      var start = minLeafSize;
64      while (start < length && attValues[start - 1].IsAlmost(attValues[start]))
65        start++;
66      if (start >= length) return;
67
68      var imp = new CorreleationImpurityCalculator(minLeafSize, attValues, targetValues, Order);
69      maxImpurity = imp.Impurity;
70      splitValues.Add(imp.SplitValue);
71      splitSizes.Add(imp.LeftSize);
72
73      while (imp.LeftSize < length - minLeafSize) {
74        imp.Increment();
75        if (!imp.ValidPosition) continue; //splits can not be made between to equal points
76
77        if (imp.Impurity.IsAlmost(maxImpurity)) {
78          splitValues.Add(imp.SplitValue);
79          splitSizes.Add(imp.LeftSize);
80          continue;
81        }
82
83        if (imp.Impurity < maxImpurity) continue;
84        splitValues.Clear();
85        splitSizes.Clear();
86        maxImpurity = imp.Impurity;
87        splitValues.Add(imp.SplitValue);
88        splitSizes.Add(imp.LeftSize);
89      }
90
91      var j = splitSizes.Count / 2;
92      if (splitSizes.Count == 0) return;
93      splitValue = splitValues[j];
94      leftSize = splitSizes[j];
95    }
96    #endregion
97  }
98}
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