Tangential_complex/example_with_perturb.cpp

#include <gudhi/Tangential_complex.h>
#include <gudhi/sparsify_point_set.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;
}