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- //
- //=======================================================================
- // 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/graph/detail/d_ary_heap.hpp>
- #include <boost/graph/breadth_first_search.hpp>
- #include <boost/iterator/reverse_iterator.hpp>
- #include <boost/concept/assert.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()
- {
- BOOST_CONCEPT_ASSERT(( 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));
- if (Q.contains(u))
- 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;
- // build the mutable queue
- typedef typename graph_traits<Graph>::vertex_descriptor vertex;
- std::vector<std::size_t> index_in_heap_data(num_vertices(g));
- typedef iterator_property_map<std::vector<std::size_t>::iterator, IndexMap>
- index_in_heap_map_type;
- index_in_heap_map_type index_in_heap_map(index_in_heap_data.begin(), im);
- typedef d_ary_heap_indirect<vertex, 4, index_in_heap_map_type, CoreMap, Cmp> MutableQueue;
- MutableQueue Q(c, index_in_heap_map, Cmp());
- 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)
- {
- 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
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