source: trunk/yat/utility/WeNNI.cc

Last change on this file was 2919, checked in by Peter, 9 years ago

update copyright years

  • Property svn:eol-style set to native
  • Property svn:keywords set to Author Date Id Revision
File size: 2.9 KB
Line 
1// $Id: WeNNI.cc 2919 2012-12-19 06:54:23Z peter $
2
3/*
4  Copyright (C) 2004 Jari Häkkinen
5  Copyright (C) 2005 Peter Johansson
6  Copyright (C) 2006 Jari Häkkinen
7  Copyright (C) 2007, 2008 Jari Häkkinen, Peter Johansson
8  Copyright (C) 2009 Jari Häkkinen
9  Copyright (C) 2011, 2012 Peter Johansson
10
11  This file is part of the yat library, http://dev.thep.lu.se/yat
12
13  The yat library is free software; you can redistribute it and/or
14  modify it under the terms of the GNU General Public License as
15  published by the Free Software Foundation; either version 3 of the
16  License, or (at your option) any later version.
17
18  The yat library is distributed in the hope that it will be useful,
19  but WITHOUT ANY WARRANTY; without even the implied warranty of
20  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21  General Public License for more details.
22
23  You should have received a copy of the GNU General Public License
24  along with yat. If not, see <http://www.gnu.org/licenses/>.
25*/
26
27#include <config.h>
28
29#include "WeNNI.h"
30#include "Matrix.h"
31#include "stl_utility.h"
32
33#include <algorithm>
34#include <cmath>
35#include <fstream>
36#include <limits>
37
38namespace theplu {
39namespace yat {
40namespace utility {
41
42
43  WeNNI::WeNNI(const utility::Matrix& matrix,const utility::Matrix& flag,
44               const unsigned int neighbours)
45    : NNI(matrix,flag,neighbours), imputed_data_raw_(matrix)
46  {
47    //estimate();
48  }
49
50
51  // \hat{x_{ij}}=\frac{ \sum_{k=1,N} \frac{w_{kj}*x_{kj}}{d_{ki}} }
52  //                   { \sum_{k=1,N} \frac{w_{kj}       }{d_{ki}} }
53  // where N is defined in the paper cited in the NNI class definition
54  // documentation.
55  unsigned int WeNNI::estimate(void)
56  {
57    double small_number=std::numeric_limits<double>::epsilon();
58    for (size_t i=0; i<data_.rows(); i++) {
59      std::vector<std::pair<size_t,double> > distance(calculate_distances(i));
60      std::sort(distance.begin(),distance.end(),
61                pair_value_compare<size_t,double>());
62      bool row_imputed=true;
63      for (size_t j=0; j<data_.columns(); j++) {
64        std::vector<size_t> knn=nearest_neighbours(j,distance);
65        double new_value=0.0;
66        double norm=0.0;
67        for (std::vector<size_t>::const_iterator k=knn.begin(); k!=knn.end();
68             ++k) {
69          // Avoid division with zero (perfect match vectors)
70          double d=(distance[*k].second ? distance[*k].second : small_number);
71          double w=weight_(distance[*k].first,j)/d;
72          if (w) {
73            new_value += w*data_(distance[*k].first,j);
74            norm      += w;
75          }
76        }
77        // No impute if no contributions from neighbours.
78        if (norm) {
79          imputed_data_raw_(i,j) = new_value/norm;
80          double w=weight_(i,j);
81          if (w)
82            imputed_data_(i,j) = w*data_(i,j) + (1-w)*imputed_data_raw_(i,j);
83          else
84            imputed_data_(i,j) = imputed_data_raw_(i,j);
85        }
86        else
87          row_imputed=false;
88      }
89      if (!row_imputed)
90        not_imputed_.push_back(i);
91    }
92    return not_imputed_.size();
93  }
94
95
96  const utility::Matrix& WeNNI::imputed_data_raw(void) const 
97  { 
98    return imputed_data_raw_; 
99  }
100
101}}} // of namespace utility, yat, and theplu
Note: See TracBrowser for help on using the repository browser.