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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): Vincent Rouvreau
*
* Copyright (C) 2018 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 CECH_COMPLEX_BLOCKER_H_
#define CECH_COMPLEX_BLOCKER_H_
#include <gudhi/Cech_complex.h> // Cech_blocker is using a pointer on Gudhi::cech_complex::Cech_complex
#include <Miniball/Miniball.hpp>
#include <iostream>
#include <vector>
#include <cmath> // for std::sqrt
namespace Gudhi {
namespace cech_complex {
// Just declaring Cech_complex class because used and not yet defined.
template<typename SimplicialComplexForCechComplex, typename ForwardPointRange>
class Cech_complex;
/** \internal
* \class Cech_blocker
* \brief Cech complex blocker.
*
* \ingroup cech_complex
*
* \details
* Cech blocker is an oracle constructed from a Cech_complex and a simplicial complex.
*
* \tparam SimplicialComplexForProximityGraph furnishes `Simplex_handle` and `Filtration_value` type definition,
* `simplex_vertex_range(Simplex_handle sh)`and `assign_filtration(Simplex_handle sh, Filtration_value filt)` methods.
*
* \tparam ForwardPointRange is required by the pointer on Chech_complex for type definition.
*/
template <typename SimplicialComplexForCech, typename ForwardPointRange>
class Cech_blocker {
private:
using Point = std::vector<double>;
using Point_cloud = std::vector<Point>;
using Point_iterator = Point_cloud::const_iterator;
using Coordinate_iterator = Point::const_iterator;
using Min_sphere = Miniball::Miniball<Miniball::CoordAccessor<Point_iterator, Coordinate_iterator>>;
using Simplex_handle = typename SimplicialComplexForCech::Simplex_handle;
using Filtration_value = typename SimplicialComplexForCech::Filtration_value;
using Cech_complex = Gudhi::cech_complex::Cech_complex<SimplicialComplexForCech, ForwardPointRange>;
public:
/** \internal \brief Cech complex blocker operator() - the oracle - assigns the filtration value from the simplex
* radius and returns if the simplex expansion must be blocked.
* \param[in] sh The Simplex_handle.
* \return true if the simplex radius is greater than the Cech_complex threshold*/
bool operator()(Simplex_handle sh) {
Point_cloud points;
for (auto vertex : simplicial_complex_.simplex_vertex_range(sh)) {
points.push_back(Point(cc_ptr_->point_iterator(vertex)->begin(),
cc_ptr_->point_iterator(vertex)->end()));
#ifdef DEBUG_TRACES
std::cout << "#(" << vertex << ")#";
#endif // DEBUG_TRACES
}
Min_sphere ms(cc_ptr_->dimension(), points.begin(),points.end());
Filtration_value diameter = 2 * std::sqrt(ms.squared_radius());
#ifdef DEBUG_TRACES
std::cout << "diameter = " << diameter << " - " << (diameter > cc_ptr_->threshold()) << std::endl;
#endif // DEBUG_TRACES
simplicial_complex_.assign_filtration(sh, diameter);
return (diameter > cc_ptr_->threshold());
}
/** \internal \brief Cech complex blocker constructor. */
Cech_blocker(SimplicialComplexForCech& simplicial_complex, Cech_complex* cc_ptr)
: simplicial_complex_(simplicial_complex),
cc_ptr_(cc_ptr) {
}
private:
SimplicialComplexForCech simplicial_complex_;
Cech_complex* cc_ptr_;
};
} // namespace cech_complex
} // namespace Gudhi
#endif // CECH_COMPLEX_BLOCKER_H_
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