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Diffstat (limited to 'trunk/src/Skeleton_blocker/example/Skeleton_blocker_iteration.cpp')
-rw-r--r-- | trunk/src/Skeleton_blocker/example/Skeleton_blocker_iteration.cpp | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/trunk/src/Skeleton_blocker/example/Skeleton_blocker_iteration.cpp b/trunk/src/Skeleton_blocker/example/Skeleton_blocker_iteration.cpp new file mode 100644 index 00000000..08ff0264 --- /dev/null +++ b/trunk/src/Skeleton_blocker/example/Skeleton_blocker_iteration.cpp @@ -0,0 +1,85 @@ +/* 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 + * + * 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 <gudhi/Skeleton_blocker.h> +#include <gudhi/Clock.h> + +#include <stdio.h> +#include <stdlib.h> +#include <string> +#include <fstream> +#include <sstream> + +typedef Gudhi::skeleton_blocker::Skeleton_blocker_simple_traits Traits; +typedef Gudhi::skeleton_blocker::Skeleton_blocker_complex<Traits> Complex; +typedef Complex::Vertex_handle Vertex_handle; +typedef Complex::Simplex 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++) + complex.add_edge_without_blockers(Vertex_handle(i), Vertex_handle(j)); + return complex; +} + +int main(int argc, char *argv[]) { + Gudhi::Clock skbl_chrono("Time to build the complete complex, enumerate simplices and Euler Characteristic"); + 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.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; + std::cout << skbl_chrono; + return EXIT_SUCCESS; +} |