Alexandria 2.31.0
SDC-CH common library for the Euclid project
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UMatrix.icpp
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1/*
2 * Copyright (C) 2012-2022 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
29namespace Euclid {
30namespace SOM {
31
32namespace UMatrix_impl {
33
34std::map<UMatrixType, std::function<double(const std::vector<double>&)>> type_func_map{
35 {UMatrixType::MIN,
36 [](const std::vector<double>& dist_list) { return *std::min_element(dist_list.begin(), dist_list.end()); }},
37 {UMatrixType::MAX,
38 [](const std::vector<double>& dist_list) { return *std::max_element(dist_list.begin(), dist_list.end()); }},
39 {UMatrixType::MEAN, [](const std::vector<double>& dist_list) {
40 return std::accumulate(dist_list.begin(), dist_list.end(), 0.) / dist_list.size();
41 }}};
42
43}
44
45template <typename DistFunc>
46UMatrix computeUMatrix(const SOM<DistFunc>& som, UMatrixType type) {
47
48 DistFunc dist_func{};
49
50 auto size = som.getSize();
51 UMatrix result = UMatrix(ImplTools::indexAxis("X", size.first), ImplTools::indexAxis("Y", size.second));
52
53 // Chose the method used for computing the u-matrix values
54 auto type_func = UMatrix_impl::type_func_map.at(type);
55
56 // Go through the SOM cells and compute the u-matrix cells
57 for (std::size_t x = 0; x < size.first; ++x) {
58 for (std::size_t y = 0; y < size.second; ++y) {
59
60 // Go through the neighbor cells and create the vector with the distances
61 std::vector<double> dist_list{};
62 for (int i = int(x) - 1; i <= (int)x + 1; ++i) {
63 for (int j = int(y) - 1; j <= (int)y + 1; ++j) {
64
65 // Check that we are not at the cell itself
66 if (i == (int)x && j == (int)y) {
67 continue;
68 }
69 // Double check that we are not outside of the SOM borders
70 if (i < 0 || i == (int)size.first || j < 0 || j == (int)size.second) {
71 continue;
72 }
73
74 auto sxy = som(x, y);
75 auto sij = som(i, j);
76 dist_list.push_back(dist_func.distance(sxy.begin(), sxy.end(), sij.begin()));
77 }
78 }
79
80 // Populate the u-matrix cell
81 result(x, y) = type_func(dist_list);
82 }
83 }
84
85 return result;
86}
87
88} // namespace SOM
89} // namespace Euclid