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/* 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): Francois Godi
*
* Copyright (C) 2015 INRIA Saclay (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 SRC_BOTTLENECK_INCLUDE_GUDHI_NEIGHBORS_FINDER_H_
#define SRC_BOTTLENECK_INCLUDE_GUDHI_NEIGHBORS_FINDER_H_
#include <unordered_set>
#include <list>
#include "gudhi/Planar_neighbors_finder.h"
namespace Gudhi {
namespace bottleneck {
// Neighbors_finder is a data structure used to find if a query point from U has neighbors in V
// in the persistence diagrams graph.
// V's points have to be added manually using their index. A neighbor returned is automatically removed.
class Neighbors_finder {
public:
Neighbors_finder(const Persistence_diagrams_graph& g, double r);
void add(int v_point_index);
int pull_near(int u_point_index);
std::list<int>* pull_all_near(int u_point_index);
private:
const Persistence_diagrams_graph& g;
const double r;
Planar_neighbors_finder planar_neighbors_f;
std::unordered_set<int> projections_f;
};
Neighbors_finder::Neighbors_finder(const Persistence_diagrams_graph& g, double r) :
g(g), r(r), planar_neighbors_f(g, r), 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
planar_neighbors_f.add(v_point_index);
}
inline int Neighbors_finder::pull_near(int u_point_index) {
int v_challenger = g.corresponding_point_in_v(u_point_index);
if (planar_neighbors_f.contains(v_challenger) && g.distance(u_point_index, v_challenger) < r) {
planar_neighbors_f.remove(v_challenger);
return v_challenger;
}
if (g.on_the_u_diagonal(u_point_index)) {
auto it = projections_f.cbegin();
if (it != projections_f.cend()) {
int tmp = *it;
projections_f.erase(it);
return tmp;
}
} else {
return planar_neighbors_f.pull_near(u_point_index);
}
return null_point_index();
}
inline std::list<int>* Neighbors_finder::pull_all_near(int u_point_index) {
std::list<int>* all_pull = planar_neighbors_f.pull_all_near(u_point_index);
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;
}
} // namespace bottleneck
} // namespace Gudhi
#endif // SRC_BOTTLENECK_INCLUDE_GUDHI_NEIGHBORS_FINDER_H_
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