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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): Clement Jamin
*
* Copyright (C) 2016 INRIA Sophia-Antipolis (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 GUDHI_SPARSIFY_POINT_SET_H
#define GUDHI_SPARSIFY_POINT_SET_H
#include <gudhi/Spatial_tree_data_structure.h>
#ifdef GUDHI_TC_PROFILING
#include <gudhi/Clock.h>
#endif
#include <cstddef>
#include <vector>
namespace Gudhi {
template <typename Kernel, typename Point_container, typename OutputIterator>
bool
sparsify_point_set(
const Kernel &k, Point_container const& input_pts,
typename Kernel::FT min_squared_dist,
OutputIterator output_it)
{
typedef typename Gudhi::Spatial_tree_data_structure<
Kernel, Point_container> Points_ds;
typename Kernel::Squared_distance_d sqdist = k.squared_distance_d_object();
#ifdef GUDHI_TC_PROFILING
Gudhi::Clock t;
#endif
Points_ds points_ds(input_pts);
std::vector<bool> dropped_points(input_pts.size(), false);
// Parse the input points, and add them if they are not too close to
// the other points
std::size_t pt_idx = 0;
for (typename Point_container::const_iterator it_pt = input_pts.begin() ;
it_pt != input_pts.end();
++it_pt, ++pt_idx)
{
if (dropped_points[pt_idx])
continue;
*output_it++ = *it_pt;
auto ins_range = points_ds.query_incremental_ANN(*it_pt);
// If another point Q is closer that min_squared_dist, mark Q to be dropped
for (auto const& neighbor : ins_range)
{
std::size_t neighbor_point_idx = neighbor.first;
// If the neighbor is too close, we drop the neighbor
if (neighbor.second < min_squared_dist)
//if (neighbor.second < 0.2*((*it_pt)[0] + 1.)*0.5 + 0.00005)
//if (neighbor.second < ((*it_pt)[0] < 0 ? 0.2 : 0.00001))
{
// N.B.: If neighbor_point_idx < pt_idx,
// dropped_points[neighbor_point_idx] is already true but adding a
// test doesn't make things faster, so why bother?
dropped_points[neighbor_point_idx] = true;
}
else
break;
}
}
#ifdef GUDHI_TC_PROFILING
t.end();
std::cerr << "Point set sparsified in " << t.num_seconds()
<< " seconds." << std::endl;
#endif
}
} //namespace Gudhi
#endif // GUDHI_POINT_CLOUD_H
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