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#include <gudhi/Alpha_complex.h>
// to construct a simplex_tree from alpha complex
#include <gudhi/Simplex_tree.h>
#include <CGAL/Epick_d.h>
#include <iostream>
#include <string>
#include <vector>
#include <limits> // for numeric limits
using Kernel = CGAL::Epick_d< CGAL::Dimension_tag<2> >;
using Point = Kernel::Point_d;
using Vector_of_points = std::vector<Point>;
void usage(int nbArgs, char * const progName) {
std::cerr << "Error: Number of arguments (" << nbArgs << ") is not correct\n";
std::cerr << "Usage: " << progName << " [alpha_square_max_value]\n";
std::cerr << " i.e.: " << progName << " 60.0\n";
exit(-1); // ----- >>
}
int main(int argc, char **argv) {
if ((argc != 1) && (argc != 2)) usage(argc, (argv[0] - 1));
// Delaunay complex if alpha_square_max_value is not given by the user.
double alpha_square_max_value {std::numeric_limits<double>::infinity()};
if (argc == 2)
alpha_square_max_value = atof(argv[1]);
// ----------------------------------------------------------------------------
// 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, alpha_square_max_value)) {
// ----------------------------------------------------------------------------
// Display information about the alpha complex
// ----------------------------------------------------------------------------
std::cout << "Alpha complex is of dimension " << simplex.dimension() <<
" - " << simplex.num_simplices() << " simplices - " <<
simplex.num_vertices() << " vertices." << std::endl;
std::cout << "Iterator on alpha complex simplices in the filtration order, with [filtration value]:" << std::endl;
for (auto f_simplex : simplex.filtration_simplex_range()) {
std::cout << " ( ";
for (auto vertex : simplex.simplex_vertex_range(f_simplex)) {
std::cout << vertex << " ";
}
std::cout << ") -> " << "[" << simplex.filtration(f_simplex) << "] ";
std::cout << std::endl;
}
}
return 0;
}
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