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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): David Salinas
*
* Copyright (C) 2014 INRIA Sophia Antipolis-Mediterranee (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/>.
*/
#include <boost/timer/timer.hpp>
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <fstream>
#include <sstream>
#include "gudhi/Skeleton_blocker.h"
using namespace std;
using namespace Gudhi;
using namespace skbl;
typedef Skeleton_blocker_complex<Skeleton_blocker_simple_traits> Complex;
typedef Complex::Vertex_handle Vertex_handle;
typedef Complex::Simplex_handle Simplex;
Complex build_complete_complex(int n){
// build a full complex with n vertices and 2^n-1 simplices
Complex complex;
for(int i=0;i<n;i++)
complex.add_vertex();
for(int i=0;i<n;i++)
for(int j=0;j<i;j++)
//note that add_edge, add the edge and all its cofaces
complex.add_edge(Vertex_handle(i),Vertex_handle(j));
return complex;
}
int main (int argc, char *argv[]){
boost::timer::auto_cpu_timer t;
const int n = 15;
// build a full complex with n vertices and 2^n-1 simplices
Complex complex(build_complete_complex(n));
// this is just to illustrate iterators, to count number of vertices
// or edges, complex.num_vertices() and complex.num_edges() are
// more appropriated!
unsigned num_vertices = 0;
for(auto v : complex.vertex_range()) {
std::cout << "Vertex " << v <<std::endl;
++num_vertices;
}
// such loop can also be done directly with distance as iterators are STL compliant
auto edges = complex.edge_range();
unsigned num_edges = std::distance(edges.begin(), edges.end());
unsigned euler = 0;
unsigned num_simplices = 0;
// we use a reference to a simplex instead of a copy
// value here because a simplex is a set of integers
// and copying it cost time
for(const Simplex & s : complex.simplex_range()){
++num_simplices;
if(s.dimension()%2 == 0)
euler += 1;
else
euler -= 1;
}
std::cout << "Saw "<<num_vertices<<" vertices, "<<num_edges<<" edges and "<<num_simplices<<" simplices"<<std::endl;
std::cout << "The Euler Characteristic is "<<euler<<std::endl;
return EXIT_SUCCESS;
}
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