Alexandria  2.22.0
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UMatrix.icpp
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1 /*
2  * Copyright (C) 2012-2021 Euclid Science Ground Segment
3  *
4  * This library is free software; you can redistribute it and/or modify it under
5  * the terms of the GNU Lesser General Public License as published by the Free
6  * Software Foundation; either version 3.0 of the License, or (at your option)
7  * any later version.
8  *
9  * This library is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
11  * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
12  * details.
13  *
14  * You should have received a copy of the GNU Lesser General Public License
15  * along with this library; if not, write to the Free Software Foundation, Inc.,
16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 /*
20  * @file UMatrix.icpp
21  * @author nikoapos
22  */
23 
24 #include "SOM/ImplTools.h"
25 #include <algorithm>
26 #include <map>
27 #include <numeric>
28 
29 namespace Euclid {
30 namespace SOM {
31 
32 namespace UMatrix_impl {
33 
34 std::map<UMatrixType, std::function<double(const std::vector<double>&)>> type_func_map{
35  {UMatrixType::MIN, [](const std::vector<double>& dist_list) { return *std::min_element(dist_list.begin(), dist_list.end()); }},
36  {UMatrixType::MAX, [](const std::vector<double>& dist_list) { return *std::max_element(dist_list.begin(), dist_list.end()); }},
37  {UMatrixType::MEAN, [](const std::vector<double>& dist_list) {
38  return std::accumulate(dist_list.begin(), dist_list.end(), 0.) / dist_list.size();
39  }}};
40 
41 }
42 
43 template <std::size_t ND, typename DistFunc>
44 UMatrix computeUMatrix(const SOM<ND, DistFunc>& som, UMatrixType type) {
45 
46  DistFunc dist_func{};
47 
48  auto size = som.getSize();
49  UMatrix result = UMatrix(ImplTools::indexAxis("X", size.first), ImplTools::indexAxis("Y", size.second));
50 
51  // Chose the method used for computing the u-matrix values
52  auto type_func = UMatrix_impl::type_func_map.at(type);
53 
54  // Go through the SOM cells and compute the u-matrix cells
55  for (std::size_t x = 0; x < size.first; ++x) {
56  for (std::size_t y = 0; y < size.second; ++y) {
57 
58  // Go through the neighbor cells and create the vector with the distances
59  std::vector<double> dist_list{};
60  for (int i = int(x) - 1; i <= (int)x + 1; ++i) {
61  for (int j = int(y) - 1; j <= (int)y + 1; ++j) {
62 
63  // Check that we are not at the cell itself
64  if (i == (int)x && j == (int)y) {
65  continue;
66  }
67  // Double check that we are not outside of the SOM borders
68  if (i < 0 || i == (int)size.first || j < 0 || j == (int)size.second) {
69  continue;
70  }
71 
72  dist_list.push_back(dist_func.distance(som(x, y), som(i, j)));
73  }
74  }
75 
76  // Populate the u-matrix cell
77  result(x, y) = type_func(dist_list);
78  }
79  }
80 
81  return result;
82 }
83 
84 } // namespace SOM
85 } // namespace Euclid