Alexandria 2.31.0
SDC-CH common library for the Euclid project
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NeihbourhoodFunc.cpp
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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
20#include <algorithm> // std::max
21#include <cmath>
22
23namespace Euclid {
24namespace SOM {
25namespace NeighborhoodFunc {
26
28 std::size_t iteration, std::size_t total_iterations) {
29 double iter_factor = 1.0 * static_cast<double>(total_iterations - iteration) / static_cast<double>(total_iterations);
30 iter_factor = iter_factor * iter_factor; // We compare the squared distances
31 auto x = static_cast<double>(bmu.first - cell.first);
32 auto y = static_cast<double>(bmu.second - cell.second);
33 double dist_square = x * x + y * y;
34 if (dist_square < m_r_square * iter_factor) {
35 return 1.;
36 } else {
37 return 0.;
38 }
39}
40
41Kohonen::Kohonen(std::size_t x_size, std::size_t y_size, double sigma_cutoff_mult)
42 : m_init_sigma(static_cast<double>(std::max(x_size, y_size)) / 2.)
43 , m_sigma_log(std::log(m_init_sigma))
44 , m_cutoff_mult_square{sigma_cutoff_mult * sigma_cutoff_mult} {}
45
46} // namespace NeighborhoodFunc
47} // namespace SOM
48} // namespace Euclid
Kohonen(std::size_t x_size, std::size_t y_size, double sigma_cutoff_mult)
double operator()(std::pair< std::size_t, std::size_t > bmu, std::pair< std::size_t, std::size_t > cell, std::size_t iteration, std::size_t total_iterations)
STL namespace.