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example_with_perturb.cpp

# Persistence_representations

#include <gudhi/Tangential_complex.h>
#include <gudhi/sparsify_point_set.h>
#include <gudhi/Simplex_tree.h>
#include <CGAL/Epick_d.h>
#include <CGAL/Random.h>
#include <array>
#include <vector>
namespace subsampl = Gudhi::subsampling;
namespace tc = Gudhi::tangential_complex;
typedef CGAL::Epick_d<CGAL::Dimension_tag < 3 >> Kernel;
typedef Kernel::FT FT;
typedef Kernel::Point_d Point;
typedef Kernel::Vector_d Vector;
typedef tc::Tangential_complex<
Kernel, CGAL::Dimension_tag<2>,
CGAL::Parallel_tag> TC;
int main(void) {
const int INTRINSIC_DIM = 2;
const int AMBIENT_DIM = 3;
const int NUM_POINTS = 50;
Kernel k;
// Generate points on a 2-sphere
CGAL::Random_points_on_sphere_d<Point> generator(AMBIENT_DIM, 3.);
std::vector<Point> points;
points.reserve(NUM_POINTS);
for (int i = 0; i < NUM_POINTS; ++i)
points.push_back(*generator++);
// Sparsify the point set
std::vector<Point> sparsified_points;
subsampl::sparsify_point_set(k, points, 0.1 * 0.1,
std::back_inserter(sparsified_points));
sparsified_points.swap(points);
// Compute the TC
TC tc(points, INTRINSIC_DIM, k);
tc.compute_tangential_complex();
// Try to fix inconsistencies. Give it 10 seconds to succeed
tc.fix_inconsistencies_using_perturbation(0.05, 10);
// Export the TC into a Simplex_tree
Gudhi::Simplex_tree<> stree;
tc.create_complex(stree);
return 0;
}
Gudhi::Simplex_tree
Simplex Tree data structure for representing simplicial complexes.
Definition Simplex_tree.h:98
Gudhi::tangential_complex::Tangential_complex
Tangential complex data structure.
Definition Tangential_complex.h:126
Gudhi::tangential_complex::Tangential_complex::fix_inconsistencies_using_perturbation
Fix_inconsistencies_info fix_inconsistencies_using_perturbation(double max_perturb, double time_limit=-1.)
Attempts to fix inconsistencies by perturbing the point positions.
Definition Tangential_complex.h:397
Gudhi::tangential_complex::Tangential_complex::compute_tangential_complex
void compute_tangential_complex()
Computes the tangential complex.
Definition Tangential_complex.h:331
Gudhi::tangential_complex::Tangential_complex::create_complex
int create_complex(Simplex_tree_ &tree, bool export_inconsistent_simplices=true) const
Exports the complex into a Simplex_tree.
Definition Tangential_complex.h:618
Gudhi::subsampling::sparsify_point_set
void sparsify_point_set(const Kernel &k, Point_range const &input_pts, typename Kernel::FT min_squared_dist, OutputIterator output_it)
Outputs a subset of the input points so that the squared distance between any two points is greater t...
Definition sparsify_point_set.h:50