| // | |
| //======================================================================= | |
| // Copyright 2007 Stanford University | |
| // Authors: David Gleich | |
| // | |
| // Distributed under the Boost Software License, Version 1.0. (See | |
| // accompanying file LICENSE_1_0.txt or copy at | |
| // http://www.boost.org/LICENSE_1_0.txt) | |
| //======================================================================= | |
| // | |
| #ifndef BOOST_GRAPH_CORE_NUMBERS_HPP | |
| #define BOOST_GRAPH_CORE_NUMBERS_HPP | |
| #include <boost/pending/mutable_queue.hpp> | |
| #include <boost/pending/indirect_cmp.hpp> | |
| #include <boost/graph/breadth_first_search.hpp> | |
| #include <boost/iterator/reverse_iterator.hpp> | |
| /* | |
| * core_numbers | |
| * | |
| * Requirement: IncidenceGraph | |
| */ | |
| // History | |
| // | |
| // 30 July 2007 | |
| // Added visitors to the implementation | |
| // | |
| // 8 February 2008 | |
| // Fixed headers and missing typename | |
| namespace boost { | |
| // A linear time O(m) algorithm to compute the indegree core number | |
| // of a graph for unweighted graphs. | |
| // | |
| // and a O((n+m) log n) algorithm to compute the in-edge-weight core | |
| // numbers of a weighted graph. | |
| // | |
| // The linear algorithm comes from: | |
| // Vladimir Batagelj and Matjaz Zaversnik, "An O(m) Algorithm for Cores | |
| // Decomposition of Networks." Sept. 1 2002. | |
| template <typename Visitor, typename Graph> | |
| struct CoreNumbersVisitorConcept { | |
| void constraints() | |
| { | |
| function_requires< CopyConstructibleConcept<Visitor> >(); | |
| vis.examine_vertex(u,g); | |
| vis.finish_vertex(u,g); | |
| vis.examine_edge(e,g); | |
| } | |
| Visitor vis; | |
| Graph g; | |
| typename graph_traits<Graph>::vertex_descriptor u; | |
| typename graph_traits<Graph>::edge_descriptor e; | |
| }; | |
| template <class Visitors = null_visitor> | |
| class core_numbers_visitor : public bfs_visitor<Visitors> { | |
| public: | |
| core_numbers_visitor() {} | |
| core_numbers_visitor(Visitors vis) | |
| : bfs_visitor<Visitors>(vis) {} | |
| private: | |
| template <class Vertex, class Graph> | |
| void initialize_vertex(Vertex, Graph&) {} | |
| template <class Vertex, class Graph> | |
| void discover_vertex(Vertex , Graph&) {} | |
| template <class Vertex, class Graph> | |
| void gray_target(Vertex, Graph&) {} | |
| template <class Vertex, class Graph> | |
| void black_target(Vertex, Graph&) {} | |
| template <class Edge, class Graph> | |
| void tree_edge(Edge, Graph&) {} | |
| template <class Edge, class Graph> | |
| void non_tree_edge(Edge, Graph&) {} | |
| }; | |
| template <class Visitors> | |
| core_numbers_visitor<Visitors> make_core_numbers_visitor(Visitors vis) | |
| { return core_numbers_visitor<Visitors>(vis); } | |
| typedef core_numbers_visitor<> default_core_numbers_visitor; | |
| namespace detail { | |
| // implement a constant_property_map to simplify compute_in_degree | |
| // for the weighted and unweighted case | |
| // this is based on dummy property map | |
| template <typename ValueType> | |
| class constant_value_property_map | |
| : public boost::put_get_helper<ValueType, | |
| constant_value_property_map<ValueType> > | |
| { | |
| public: | |
| typedef void key_type; | |
| typedef ValueType value_type; | |
| typedef const ValueType& reference; | |
| typedef boost::readable_property_map_tag category; | |
| inline constant_value_property_map(ValueType cc) : c(cc) { } | |
| inline constant_value_property_map(const constant_value_property_map<ValueType>& x) | |
| : c(x.c) { } | |
| template <class Vertex> | |
| inline reference operator[](Vertex) const { return c; } | |
| protected: | |
| ValueType c; | |
| }; | |
| // the core numbers start as the indegree or inweight. This function | |
| // will initialize these values | |
| template <typename Graph, typename CoreMap, typename EdgeWeightMap> | |
| void compute_in_degree_map(Graph& g, CoreMap d, EdgeWeightMap wm) | |
| { | |
| typename graph_traits<Graph>::vertex_iterator vi,vi_end; | |
| typename graph_traits<Graph>::out_edge_iterator ei,ei_end; | |
| for (boost::tie(vi,vi_end) = vertices(g); vi!=vi_end; ++vi) { | |
| put(d,*vi,0); | |
| } | |
| for (boost::tie(vi,vi_end) = vertices(g); vi!=vi_end; ++vi) { | |
| for (boost::tie(ei,ei_end) = out_edges(*vi,g); ei!=ei_end; ++ei) { | |
| put(d,target(*ei,g),get(d,target(*ei,g))+get(wm,*ei)); | |
| } | |
| } | |
| } | |
| // the version for weighted graphs is a little different | |
| template <typename Graph, typename CoreMap, | |
| typename EdgeWeightMap, typename MutableQueue, | |
| typename Visitor> | |
| typename property_traits<CoreMap>::value_type | |
| core_numbers_impl(Graph& g, CoreMap c, EdgeWeightMap wm, | |
| MutableQueue& Q, Visitor vis) | |
| { | |
| typename property_traits<CoreMap>::value_type v_cn = 0; | |
| typedef typename graph_traits<Graph>::vertex_descriptor vertex; | |
| while (!Q.empty()) | |
| { | |
| // remove v from the Q, and then decrease the core numbers | |
| // of its successors | |
| vertex v = Q.top(); | |
| vis.examine_vertex(v,g); | |
| Q.pop(); | |
| v_cn = get(c,v); | |
| typename graph_traits<Graph>::out_edge_iterator oi,oi_end; | |
| for (boost::tie(oi,oi_end) = out_edges(v,g); oi!=oi_end; ++oi) { | |
| vis.examine_edge(*oi,g); | |
| vertex u = target(*oi,g); | |
| // if c[u] > c[v], then u is still in the graph, | |
| if (get(c,u) > v_cn) { | |
| // remove the edge | |
| put(c,u,get(c,u)-get(wm,*oi)); | |
| Q.update(u); | |
| } | |
| } | |
| vis.finish_vertex(v,g); | |
| } | |
| return (v_cn); | |
| } | |
| template <typename Graph, typename CoreMap, typename EdgeWeightMap, | |
| typename IndexMap, typename CoreNumVisitor> | |
| typename property_traits<CoreMap>::value_type | |
| core_numbers_dispatch(Graph&g, CoreMap c, EdgeWeightMap wm, | |
| IndexMap im, CoreNumVisitor vis) | |
| { | |
| typedef typename property_traits<CoreMap>::value_type D; | |
| typedef std::less<D> Cmp; | |
| typedef indirect_cmp<CoreMap,Cmp > IndirectCmp; | |
| IndirectCmp icmp(c, Cmp()); | |
| // build the mutable queue | |
| typedef typename graph_traits<Graph>::vertex_descriptor vertex; | |
| typedef mutable_queue<vertex, std::vector<vertex>, IndirectCmp, | |
| IndexMap> MutableQueue; | |
| MutableQueue Q(num_vertices(g), icmp, im); | |
| typename graph_traits<Graph>::vertex_iterator vi,vi_end; | |
| for (boost::tie(vi,vi_end) = vertices(g); vi!=vi_end; ++vi) { | |
| Q.push(*vi); | |
| } | |
| return core_numbers_impl(g, c, wm, Q, vis); | |
| } | |
| // the version for the unweighted case | |
| // for this functions CoreMap must be initialized | |
| // with the in degree of each vertex | |
| template <typename Graph, typename CoreMap, typename PositionMap, | |
| typename Visitor> | |
| typename property_traits<CoreMap>::value_type | |
| core_numbers_impl(Graph& g, CoreMap c, PositionMap pos, Visitor vis) | |
| { | |
| typedef typename graph_traits<Graph>::vertices_size_type size_type; | |
| typedef typename graph_traits<Graph>::degree_size_type degree_type; | |
| typedef typename graph_traits<Graph>::vertex_descriptor vertex; | |
| typename graph_traits<Graph>::vertex_iterator vi,vi_end; | |
| // store the vertex core numbers | |
| typename property_traits<CoreMap>::value_type v_cn = 0; | |
| // compute the maximum degree (degrees are in the coremap) | |
| typename graph_traits<Graph>::degree_size_type max_deg = 0; | |
| for (boost::tie(vi,vi_end) = vertices(g); vi!=vi_end; ++vi) { | |
| max_deg = (std::max<typename graph_traits<Graph>::degree_size_type>)(max_deg, get(c,*vi)); | |
| } | |
| // store the vertices in bins by their degree | |
| // allocate two extra locations to ease boundary cases | |
| std::vector<size_type> bin(max_deg+2); | |
| for (boost::tie(vi,vi_end) = vertices(g); vi!=vi_end; ++vi) { | |
| ++bin[get(c,*vi)]; | |
| } | |
| // this loop sets bin[d] to the starting position of vertices | |
| // with degree d in the vert array for the bucket sort | |
| size_type cur_pos = 0; | |
| for (degree_type cur_deg = 0; cur_deg < max_deg+2; ++cur_deg) { | |
| degree_type tmp = bin[cur_deg]; | |
| bin[cur_deg] = cur_pos; | |
| cur_pos += tmp; | |
| } | |
| // perform the bucket sort with pos and vert so that | |
| // pos[0] is the vertex of smallest degree | |
| std::vector<vertex> vert(num_vertices(g)); | |
| for (boost::tie(vi,vi_end) = vertices(g); vi!=vi_end; ++vi) { | |
| vertex v=*vi; | |
| size_type p=bin[get(c,v)]; | |
| put(pos,v,p); | |
| vert[p]=v; | |
| ++bin[get(c,v)]; | |
| } | |
| // we ``abused'' bin while placing the vertices, now, | |
| // we need to restore it | |
| std::copy(boost::make_reverse_iterator(bin.end()-2), | |
| boost::make_reverse_iterator(bin.begin()), | |
| boost::make_reverse_iterator(bin.end()-1)); | |
| // now simulate removing the vertices | |
| for (size_type i=0; i < num_vertices(g); ++i) { | |
| vertex v = vert[i]; | |
| vis.examine_vertex(v,g); | |
| v_cn = get(c,v); | |
| typename graph_traits<Graph>::out_edge_iterator oi,oi_end; | |
| for (boost::tie(oi,oi_end) = out_edges(v,g); oi!=oi_end; ++oi) { | |
| vis.examine_edge(*oi,g); | |
| vertex u = target(*oi,g); | |
| // if c[u] > c[v], then u is still in the graph, | |
| if (get(c,u) > v_cn) { | |
| degree_type deg_u = get(c,u); | |
| degree_type pos_u = get(pos,u); | |
| // w is the first vertex with the same degree as u | |
| // (this is the resort operation!) | |
| degree_type pos_w = bin[deg_u]; | |
| vertex w = vert[pos_w]; | |
| if (u!=v) { | |
| // swap u and w | |
| put(pos,u,pos_w); | |
| put(pos,w,pos_u); | |
| vert[pos_w] = u; | |
| vert[pos_u] = w; | |
| } | |
| // now, the vertices array is sorted assuming | |
| // we perform the following step | |
| // start the set of vertices with degree of u | |
| // one into the future (this now points at vertex | |
| // w which we swapped with u). | |
| ++bin[deg_u]; | |
| // we are removing v from the graph, so u's degree | |
| // decreases | |
| put(c,u,get(c,u)-1); | |
| } | |
| } | |
| vis.finish_vertex(v,g); | |
| } | |
| return v_cn; | |
| } | |
| } // namespace detail | |
| // non-named parameter version for the unweighted case | |
| template <typename Graph, typename CoreMap, typename CoreNumVisitor> | |
| typename property_traits<CoreMap>::value_type | |
| core_numbers(Graph& g, CoreMap c, CoreNumVisitor vis) | |
| { | |
| typedef typename graph_traits<Graph>::vertices_size_type size_type; | |
| detail::compute_in_degree_map(g,c, | |
| detail::constant_value_property_map< | |
| typename property_traits<CoreMap>::value_type>(1) ); | |
| return detail::core_numbers_impl(g,c, | |
| make_iterator_property_map( | |
| std::vector<size_type>(num_vertices(g)).begin(),get(vertex_index, g)), | |
| vis | |
| ); | |
| } | |
| // non-named paramter version for the unweighted case | |
| template <typename Graph, typename CoreMap> | |
| typename property_traits<CoreMap>::value_type | |
| core_numbers(Graph& g, CoreMap c) | |
| { | |
| return core_numbers(g, c, make_core_numbers_visitor(null_visitor())); | |
| } | |
| // non-named parameter version for the weighted case | |
| template <typename Graph, typename CoreMap, typename EdgeWeightMap, | |
| typename VertexIndexMap, typename CoreNumVisitor> | |
| typename property_traits<CoreMap>::value_type | |
| core_numbers(Graph& g, CoreMap c, EdgeWeightMap wm, VertexIndexMap vim, | |
| CoreNumVisitor vis) | |
| { | |
| typedef typename graph_traits<Graph>::vertices_size_type size_type; | |
| detail::compute_in_degree_map(g,c,wm); | |
| return detail::core_numbers_dispatch(g,c,wm,vim,vis); | |
| } | |
| // non-named parameter version for the weighted case | |
| // template <typename Graph, typename CoreMap, typename EdgeWeightMap> | |
| // typename property_traits<CoreMap>::value_type | |
| // core_numbers(Graph& g, CoreMap c, EdgeWeightMap wm) | |
| // { | |
| // typedef typename graph_traits<Graph>::vertices_size_type size_type; | |
| // detail::compute_in_degree_map(g,c,wm); | |
| // return detail::core_numbers_dispatch(g,c,wm,get(vertex_index,g), | |
| // make_core_numbers_visitor(null_visitor())); | |
| // } | |
| template <typename Graph, typename CoreMap> | |
| typename property_traits<CoreMap>::value_type | |
| weighted_core_numbers(Graph& g, CoreMap c) | |
| { | |
| return weighted_core_numbers( | |
| g,c, make_core_numbers_visitor(null_visitor()) | |
| ); | |
| } | |
| template <typename Graph, typename CoreMap, typename CoreNumVisitor> | |
| typename property_traits<CoreMap>::value_type | |
| weighted_core_numbers(Graph& g, CoreMap c, CoreNumVisitor vis) | |
| { return core_numbers(g,c,get(edge_weight,g),get(vertex_index,g),vis); } | |
| } // namespace boost | |
| #endif // BOOST_GRAPH_CORE_NUMBERS_HPP | |