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Diffstat (limited to 'trunk/src/GudhUI/utils/Lloyd_builder.h')
-rw-r--r-- | trunk/src/GudhUI/utils/Lloyd_builder.h | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/trunk/src/GudhUI/utils/Lloyd_builder.h b/trunk/src/GudhUI/utils/Lloyd_builder.h new file mode 100644 index 00000000..18ec9fac --- /dev/null +++ b/trunk/src/GudhUI/utils/Lloyd_builder.h @@ -0,0 +1,91 @@ +/* This file is part of the Gudhi Library. The Gudhi library + * (Geometric Understanding in Higher Dimensions) is a generic C++ + * library for computational topology. + * + * Author(s): David Salinas + * + * Copyright (C) 2014 INRIA Sophia Antipolis-Mediterranee (France) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * + */ + +#ifndef UTILS_LLOYD_BUILDER_H_ +#define UTILS_LLOYD_BUILDER_H_ + +#include <vector> +#include <list> + +/** + * Iteratively puts every vertex at the center of its neighbors + */ +template<typename SkBlComplex> class Lloyd_builder { + private: + SkBlComplex& complex_; + int dim; + + public: + typedef typename SkBlComplex::Vertex_handle Vertex_handle; + + /** + * @brief Modify complex to be the expansion of the k-nearest neighbor + * symetric graph. + */ + Lloyd_builder(SkBlComplex& complex, unsigned num_iterations) : complex_(complex), dim(-1) { + if (!complex_.empty()) { + dim = get_dimension(); + while (num_iterations--) { + std::list<Point> new_points; + for (auto v : complex.vertex_range()) + new_points.push_back(barycenter_neighbors(v)); + + auto new_points_it = new_points.begin(); + for (auto v : complex.vertex_range()) + complex_.point(v) = *(new_points_it++); + } + } + } + + private: + int get_dimension() { + assert(!complex_.empty()); + for (auto v : complex_.vertex_range()) + return complex_.point(v).dimension(); + return -1; + } + + Point barycenter_neighbors(Vertex_handle v) const { + if (complex_.degree(v) == 0) + return complex_.point(v); + + std::vector<double> res(dim, 0); + unsigned num_points = 0; + for (auto nv : complex_.vertex_range(v)) { + ++num_points; + const Point& point = complex_.point(nv); + assert(point.dimension() == dim); + for (int i = 0; i < point.dimension(); ++i) + res[i] += point[i]; + } + for (auto& x : res) + x /= num_points; + return Point(dim, res.begin(), res.end()); + } + + double squared_eucl_distance(const Point& p1, const Point& p2) const { + return Geometry_trait::Squared_distance_d()(p1, p2); + } +}; + +#endif // UTILS_LLOYD_BUILDER_H_ |