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source: trunk/sources/HeuristicLab.Algorithms.DataAnalysis/3.4/TSNE/Distances/CosineDistance.cs @ 15532

Last change on this file since 15532 was 15532, checked in by bwerth, 5 years ago

#2850 merged Weighted TSNE to trunk

File size: 2.8 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2016 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;
23using System.Collections.Generic;
24using HeuristicLab.Common;
25using HeuristicLab.Core;
26using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
27
28namespace HeuristicLab.Algorithms.DataAnalysis {
29  /// <summary>
30  /// The angular distance as defined as a normalized distance measure dependent on the angle between two vectors.
31  /// </summary>
32  [StorableClass]
33  [Item("CosineDistance", "The angular distance as defined as a normalized distance measure dependent on the angle between two vectors.")]
34  public class CosineDistance : DistanceBase<IEnumerable<double>> {
35    #region HLConstructors & Cloning
36    [StorableConstructor]
37    protected CosineDistance(bool deserializing) : base(deserializing) { }
38    protected CosineDistance(CosineDistance original, Cloner cloner)
39      : base(original, cloner) { }
40    public CosineDistance() { }
41    public override IDeepCloneable Clone(Cloner cloner) {
42      return new CosineDistance(this, cloner);
43    }
44    #endregion
45
46    #region statics
47    public static double GetDistance(IEnumerable<double> point1, IEnumerable<double> point2) {
48      using (IEnumerator<double> p1Enum = point1.GetEnumerator(), p2Enum = point2.GetEnumerator()) {
49        var innerprod = 0.0;
50        var length1 = 0.0;
51        var length2 = 0.0;
52        while (p1Enum.MoveNext() & p2Enum.MoveNext()) {
53          double d1 = p1Enum.Current, d2 = p2Enum.Current;
54          innerprod += d1 * d2;
55          length1 += d1 * d1;
56          length2 += d2 * d2;
57        }
58        var divisor = Math.Sqrt(length1 * length2);
59        if (divisor.IsAlmost(0)) throw new ArgumentException("Cosine distance is not defined on vectors of length 0");
60        if (p1Enum.MoveNext() || p2Enum.MoveNext()) throw new ArgumentException("Cosine distance not defined on vectors of different length");
61        return 1 - innerprod / divisor;
62      }
63    }
64    #endregion
65    public override double Get(IEnumerable<double> a, IEnumerable<double> b) {
66      return GetDistance(a, b);
67    }
68  }
69}
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