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source: branches/FitnessLandscapeAnalysis/HeuristicLab.Analysis.FitnessLandscape/Analysis/EnumerableExtensions.cs @ 11761

Last change on this file since 11761 was 7128, checked in by epitzer, 13 years ago

#1696 Integrate fitness landscape analysis plugins from Heureka! repository.

File size: 2.2 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2010 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
21using System;
22using System.Collections.Generic;
23namespace HeuristicLab.Analysis.FitnessLandscape {
24
25  public static class Utils {
26
27    public static IEnumerable<TResult> Delta<T, TResult>(this IEnumerable<T> values, Func<T, T, TResult> f) {
28      var it = values.GetEnumerator();
29      T last = default(T);
30      if (it.MoveNext())
31        last = it.Current;
32      while (it.MoveNext()) {
33        yield return f(last, it.Current);
34        last = it.Current;
35      }
36    }
37
38    public static IEnumerable<IEnumerable<TSource>> GroupConsecutive<TSource, TKey>(
39        this IEnumerable<TSource> source, Func<TSource, TKey> keySelector) {
40      if (source == null) throw new ArgumentNullException("source");
41      if (keySelector == null) throw new ArgumentNullException("keySelector");
42
43      var comparer = EqualityComparer<TKey>.Default;
44      var grouped = new List<TSource>();
45      using (var iter = source.GetEnumerator()) {
46        if (!iter.MoveNext()) yield break;
47        grouped.Add(iter.Current);
48        var last = iter.Current;
49        while (iter.MoveNext()) {
50          if (!comparer.Equals(keySelector(iter.Current), keySelector(last))) {
51            yield return grouped.AsReadOnly();
52            grouped = new List<TSource>();
53          }
54          grouped.Add(iter.Current);
55          last = iter.Current;
56        }
57        yield return grouped.AsReadOnly();
58      }
59    }
60  }
61}
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