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Diffstat (limited to 'include/gudhi/graph_simplicial_complex.h')
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diff --git a/include/gudhi/graph_simplicial_complex.h b/include/gudhi/graph_simplicial_complex.h new file mode 100644 index 00000000..042ef516 --- /dev/null +++ b/include/gudhi/graph_simplicial_complex.h @@ -0,0 +1,99 @@ +/* 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): Clément Maria + * + * Copyright (C) 2014 INRIA Sophia Antipolis-Méditerranée (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/>. + */ + +#ifndef GRAPH_SIMPLICIAL_COMPLEX_H_ +#define GRAPH_SIMPLICIAL_COMPLEX_H_ + +#include <boost/graph/adjacency_list.hpp> + +#include <utility> // for pair<> +#include <vector> +#include <map> + +/* Edge tag for Boost PropertyGraph. */ +struct edge_filtration_t { + typedef boost::edge_property_tag kind; +}; + +/* Vertex tag for Boost PropertyGraph. */ +struct vertex_filtration_t { + typedef boost::vertex_property_tag kind; +}; + +typedef int Vertex_handle; +typedef double Filtration_value; +typedef boost::adjacency_list < boost::vecS, boost::vecS, boost::undirectedS +, boost::property < vertex_filtration_t, Filtration_value > +, boost::property < edge_filtration_t, Filtration_value > +> Graph_t; +typedef std::pair< Vertex_handle, Vertex_handle > Edge_t; + +/** \brief Output the proximity graph of the points. + * + * If points contains n elements, the proximity graph is the graph + * with n vertices, and an edge [u,v] iff the distance function between + * points u and v is smaller than threshold. + * + * The type PointCloud furnishes .begin() and .end() methods, that return + * iterators with value_type Point. + */ +template< typename PointCloud +, typename Point > +Graph_t compute_proximity_graph(PointCloud &points + , Filtration_value threshold + , Filtration_value distance(Point p1, Point p2)) { + std::vector< Edge_t > edges; + std::vector< Filtration_value > edges_fil; + std::map< Vertex_handle, Filtration_value > vertices; + + Vertex_handle idx_u, idx_v; + Filtration_value fil; + idx_u = 0; + for (auto it_u = points.begin(); it_u != points.end(); ++it_u) { + idx_v = idx_u + 1; + for (auto it_v = it_u + 1; it_v != points.end(); ++it_v, ++idx_v) { + fil = distance(*it_u, *it_v); + if (fil <= threshold) { + edges.emplace_back(idx_u, idx_v); + edges_fil.push_back(fil); + } + } + ++idx_u; + } + + Graph_t skel_graph(edges.begin() + , edges.end() + , edges_fil.begin() + , idx_u); // number of points labeled from 0 to idx_u-1 + + auto vertex_prop = boost::get(vertex_filtration_t(), skel_graph); + + boost::graph_traits<Graph_t>::vertex_iterator vi, vi_end; + for (std::tie(vi, vi_end) = boost::vertices(skel_graph); + vi != vi_end; ++vi) { + boost::put(vertex_prop, *vi, 0.); + } + + return skel_graph; +} + +#endif // GRAPH_SIMPLICIAL_COMPLEX_H_ |