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Diffstat (limited to 'src/Bottleneck_distance/include/gudhi/Neighbors_finder.h')
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1 files changed, 171 insertions, 0 deletions
diff --git a/src/Bottleneck_distance/include/gudhi/Neighbors_finder.h b/src/Bottleneck_distance/include/gudhi/Neighbors_finder.h new file mode 100644 index 00000000..96ece360 --- /dev/null +++ b/src/Bottleneck_distance/include/gudhi/Neighbors_finder.h @@ -0,0 +1,171 @@ +/* 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: Francois Godi + * + * Copyright (C) 2015 INRIA + * + * 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 NEIGHBORS_FINDER_H_ +#define NEIGHBORS_FINDER_H_ + +// Inclusion order is important for CGAL patch +#include <CGAL/Kd_tree.h> +#include <CGAL/Kd_tree_node.h> +#include <CGAL/Orthogonal_k_neighbor_search.h> +#include <CGAL/Weighted_Minkowski_distance.h> +#include <CGAL/Search_traits.h> + +#include <gudhi/Persistence_graph.h> +#include <gudhi/Internal_point.h> + +#include <unordered_set> + +namespace Gudhi { + +namespace persistence_diagram { + +/** \internal \brief data structure used to find any point (including projections) in V near to a query point from U + * (which can be a projection). + * + * V points have to be added manually using their index and before the first pull. A neighbor pulled is automatically + * removed. + * + * \ingroup bottleneck_distance + */ +class Neighbors_finder { + typedef CGAL::Dimension_tag<2> D; + typedef CGAL::Search_traits<double, Internal_point, const double*, Construct_coord_iterator, D> Traits; + typedef CGAL::Weighted_Minkowski_distance<Traits> Distance; + typedef CGAL::Orthogonal_k_neighbor_search<Traits, Distance> K_neighbor_search; + typedef K_neighbor_search::Tree Kd_tree; + + public: + /** \internal \brief Constructor taking the near distance definition as parameter. */ + Neighbors_finder(const Persistence_graph& g, double r); + /** \internal \brief A point added will be possibly pulled. */ + void add(int v_point_index); + /** \internal \brief Returns and remove a V point near to the U point given as parameter, null_point_index() if + * there isn't such a point. */ + int pull_near(int u_point_index); + /** \internal \brief Returns and remove all the V points near to the U point given as parameter. */ + std::vector<int> pull_all_near(int u_point_index); + + private: + const Persistence_graph& g; + const double r; + Kd_tree kd_t; + std::unordered_set<int> projections_f; +}; + +/** \internal \brief data structure used to find any point (including projections) in V near to a query point from U + * (which can be a projection) in a layered graph layer given as parmeter. + * + * V points have to be added manually using their index and before the first pull. A neighbor pulled is automatically + * removed. + * + * \ingroup bottleneck_distance + */ +class Layered_neighbors_finder { + public: + /** \internal \brief Constructor taking the near distance definition as parameter. */ + Layered_neighbors_finder(const Persistence_graph& g, double r); + /** \internal \brief A point added will be possibly pulled. */ + void add(int v_point_index, int vlayer); + /** \internal \brief Returns and remove a V point near to the U point given as parameter, null_point_index() if + * there isn't such a point. */ + int pull_near(int u_point_index, int vlayer); + /** \internal \brief Returns the number of layers. */ + int vlayers_number() const; + + private: + const Persistence_graph& g; + const double r; + std::vector<std::unique_ptr<Neighbors_finder>> neighbors_finder; +}; + +inline Neighbors_finder::Neighbors_finder(const Persistence_graph& g, double r) : + g(g), r(r), kd_t(), projections_f() { } + +inline void Neighbors_finder::add(int v_point_index) { + if (g.on_the_v_diagonal(v_point_index)) + projections_f.emplace(v_point_index); + else + kd_t.insert(g.get_v_point(v_point_index)); +} + +inline int Neighbors_finder::pull_near(int u_point_index) { + int tmp; + int c = g.corresponding_point_in_v(u_point_index); + if (g.on_the_u_diagonal(u_point_index) && !projections_f.empty()) { + // Any pair of projection is at distance 0 + tmp = *projections_f.cbegin(); + projections_f.erase(tmp); + } else if (projections_f.count(c) && (g.distance(u_point_index, c) <= r)) { + // Is the query point near to its projection ? + tmp = c; + projections_f.erase(tmp); + } else { + // Is the query point near to a V point in the plane ? + Internal_point u_point = g.get_u_point(u_point_index); + std::array<double, 2> w = { + {1., 1.} + }; + K_neighbor_search search(kd_t, u_point, 1, 0., true, Distance(0, 2, w.begin(), w.end())); + auto it = search.begin(); + if (it == search.end() || g.distance(u_point_index, it->first.point_index) > r) + return null_point_index(); + tmp = it->first.point_index; + kd_t.remove(g.get_v_point(tmp)); + } + return tmp; +} + +inline std::vector<int> Neighbors_finder::pull_all_near(int u_point_index) { + std::vector<int> all_pull; + int last_pull = pull_near(u_point_index); + while (last_pull != null_point_index()) { + all_pull.emplace_back(last_pull); + last_pull = pull_near(u_point_index); + } + return all_pull; +} + +inline Layered_neighbors_finder::Layered_neighbors_finder(const Persistence_graph& g, double r) : + g(g), r(r), neighbors_finder() { } + +inline void Layered_neighbors_finder::add(int v_point_index, int vlayer) { + for (int l = neighbors_finder.size(); l <= vlayer; l++) + neighbors_finder.emplace_back(std::unique_ptr<Neighbors_finder>(new Neighbors_finder(g, r))); + neighbors_finder.at(vlayer)->add(v_point_index); +} + +inline int Layered_neighbors_finder::pull_near(int u_point_index, int vlayer) { + if (static_cast<int> (neighbors_finder.size()) <= vlayer) + return null_point_index(); + return neighbors_finder.at(vlayer)->pull_near(u_point_index); +} + +inline int Layered_neighbors_finder::vlayers_number() const { + return static_cast<int> (neighbors_finder.size()); +} + +} // namespace persistence_diagram + +} // namespace Gudhi + +#endif // NEIGHBORS_FINDER_H_ |