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Alpha_complex_from_points.cpp

# Skeleton_blocker

#include <gudhi/Alpha_complex.h>
// to construct a simplex_tree from alpha complex
#include <gudhi/Simplex_tree.h>
#include <CGAL/Epeck_d.h>
#include <iostream>
#include <vector>
// Explicit dimension 2 Epeck_d kernel
using Kernel = CGAL::Epeck_d< CGAL::Dimension_tag<2> >;
using Point = Kernel::Point_d;
using Vector_of_points = std::vector<Point>;
int main() {
// ----------------------------------------------------------------------------
// Init of a list of points
// ----------------------------------------------------------------------------
Vector_of_points points;
points.push_back(Point(1.0, 1.0));
points.push_back(Point(7.0, 0.0));
points.push_back(Point(4.0, 6.0));
points.push_back(Point(9.0, 6.0));
points.push_back(Point(0.0, 14.0));
points.push_back(Point(2.0, 19.0));
points.push_back(Point(9.0, 17.0));
// ----------------------------------------------------------------------------
// Init of an alpha complex from the list of points
// ----------------------------------------------------------------------------
Gudhi::alpha_complex::Alpha_complex<Kernel> alpha_complex_from_points(points);
Gudhi::Simplex_tree<> simplex;
if (alpha_complex_from_points.create_complex(simplex)) {
// ----------------------------------------------------------------------------
// Display information about the alpha complex
// ----------------------------------------------------------------------------
std::clog << "Alpha complex is of dimension " << simplex.dimension() <<
" - " << simplex.num_simplices() << " simplices - " <<
simplex.num_vertices() << " vertices." << std::endl;
std::clog << "Iterator on alpha complex simplices in the filtration order, with [filtration value]:" << std::endl;
for (auto f_simplex : simplex.filtration_simplex_range()) {
std::clog << " ( ";
for (auto vertex : simplex.simplex_vertex_range(f_simplex)) {
std::clog << vertex << " ";
}
std::clog << ") -> " << "[" << simplex.filtration(f_simplex) << "] ";
std::clog << std::endl;
}
}
return 0;
}
Gudhi::Simplex_tree
Simplex Tree data structure for representing simplicial complexes.
Definition Simplex_tree.h:98
Gudhi::Simplex_tree::simplex_vertex_range
Simplex_vertex_range simplex_vertex_range(Simplex_handle sh) const
Returns a range over the vertices of a simplex.
Definition Simplex_tree.h:369
Gudhi::Simplex_tree::filtration
static Filtration_value filtration(Simplex_handle sh)
Returns the filtration value of a simplex.
Definition Simplex_tree.h:727
Gudhi::Simplex_tree::filtration_simplex_range
Filtration_simplex_range const & filtration_simplex_range(Indexing_tag=Indexing_tag()) const
Returns a range over the simplices of the simplicial complex, in the order of the filtration.
Definition Simplex_tree.h:358
Gudhi::Simplex_tree::num_vertices
size_t num_vertices() const
Returns the number of vertices in the complex.
Definition Simplex_tree.h:778
Gudhi::Simplex_tree::num_simplices
size_t num_simplices() const
Returns the number of simplices in the simplex_tree.
Definition Simplex_tree.h:791
Gudhi::alpha_complex::Alpha_complex
Alpha complex data structure.
Definition Alpha_complex.h:103
Gudhi::alpha_complex::Alpha_complex::create_complex
bool create_complex(SimplicialComplexForAlpha &complex, Filtration_value max_alpha_square=std::numeric_limits< Filtration_value >::infinity(), bool exact=false, bool default_filtration_value=false)
Inserts all Delaunay triangulation into the simplicial complex. It also computes the filtration value...
Definition Alpha_complex.h:386