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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): David Salinas
*
* Copyright (C) 2014 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 UTILS_EDGE_CONTRACTOR_H_
#define UTILS_EDGE_CONTRACTOR_H_
#include <gudhi/Skeleton_blocker_contractor.h>
#include <gudhi/Contraction/Edge_profile.h>
#include <gudhi/Contraction/policies/Cost_policy.h>
#include <vector>
/**
* Iteratively puts every vertex at the center of its neighbors
*/
template<typename SkBlComplex> class Edge_contractor {
private:
SkBlComplex& complex_;
unsigned num_contractions_;
/**
* @brief return a cost corresponding to the squared length of the edge
*/
template< typename EdgeProfile> class Length_cost : public contraction::Cost_policy<EdgeProfile> {
public:
typedef typename contraction::Cost_policy<EdgeProfile>::Cost_type Cost_type;
typedef typename EdgeProfile::Point Point;
Cost_type operator()(const EdgeProfile& profile, const boost::optional<Point>& placement) const override {
Cost_type res;
if (!placement)
return res;
return Geometry_trait::Squared_distance_d()(profile.p0(), profile.p1()); // not working??
}
};
/**
* @brief return a cost corresponding to the squared length of the edge
*/
template< typename EdgeProfile> class Middle_placement : public contraction::Placement_policy<EdgeProfile> {
public:
typedef typename contraction::Placement_policy<EdgeProfile>::Placement_type Placement_type;
typedef typename EdgeProfile::Point Point;
Placement_type operator()(const EdgeProfile& profile) const override {
std::vector<double> mid_coords(profile.p0().dimension(), 0);
for (int i = 0; i < profile.p0().dimension(); ++i) {
mid_coords[i] = (profile.p0()[i] + profile.p1()[i]) / 2.;
}
return Point(profile.p0().dimension(), mid_coords.begin(), mid_coords.end());
}
};
public:
typedef typename SkBlComplex::Vertex_handle Vertex_handle;
typedef typename SkBlComplex::Edge_handle Edge_handle;
/**
* @brief Modify complex to be the expansion of the k-nearest neighbor
* symetric graph.
*/
Edge_contractor(SkBlComplex& complex, unsigned num_contractions) :
complex_(complex), num_contractions_(num_contractions) {
typedef typename contraction::Edge_profile<Complex> Profile;
num_contractions = (std::min)(static_cast<int>(num_contractions), static_cast<int>(complex_.num_vertices() - 1));
typedef typename contraction::Skeleton_blocker_contractor<Complex> Contractor;
Contractor contractor(complex_,
new Length_cost<contraction::Edge_profile < Complex >> (),
new Middle_placement<contraction::Edge_profile < Complex >> (),
contraction::make_link_valid_contraction<Profile>(),
contraction::make_remove_popable_blockers_visitor<Profile>());
contractor.contract_edges(num_contractions);
}
};
#endif // UTILS_EDGE_CONTRACTOR_H_
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