[Boost-commit] svn:boost r38402 - sandbox/SOC/2007/graphs/boost/graph

From: asutton_at_[hidden]
Date: 2007-08-02 12:17:09

Author: asutton
Date: 2007-08-02 12:17:08 EDT (Thu, 02 Aug 2007)
New Revision: 38402
URL: http://svn.boost.org/trac/boost/changeset/38402

Log:
Importing core numbers impl

Added:
   sandbox/SOC/2007/graphs/boost/graph/core_numbers.hpp   (contents, props changed)

Added: sandbox/SOC/2007/graphs/boost/graph/core_numbers.hpp
==============================================================================
--- (empty file)
+++ sandbox/SOC/2007/graphs/boost/graph/core_numbers.hpp	2007-08-02 12:17:08 EDT (Thu, 02 Aug 2007)
@@ -0,0 +1,259 @@
+//=======================================================================
+// 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>
+
+/*
+ *KCore
+ *
+ *Requirement:
+ *      IncidenceGraph
+ */
+
+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.
+    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 (tie(vi,vi_end) = vertices(g); vi!=vi_end; ++vi) {
+                put(d,*vi,0);
+            }
+            for (tie(vi,vi_end) = vertices(g); vi!=vi_end; ++vi) {
+                for (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 property_traits<CoreMap>::value_type
+        core_numbers_impl(Graph& g, CoreMap c, EdgeWeightMap wm,
+            MutableQueue& Q)
+        {
+            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();
+                Q.pop();
+                v_cn = get(c,v);
+                typename graph_traits<Graph>::out_edge_iterator oi,oi_end;
+                for (tie(oi,oi_end) = out_edges(v,g); oi!=oi_end; ++oi) {
+                    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);
+                    }
+                }
+            }
+            return (v_cn);
+        }
+
+        template <typename Graph, typename CoreMap, typename EdgeWeightMap,
+            typename IndexMap>
+        typename property_traits<CoreMap>::value_type
+        core_numbers_dispatch(Graph&g, CoreMap c, EdgeWeightMap wm,
+            IndexMap im)
+        {
+            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 (tie(vi,vi_end) = vertices(g); vi!=vi_end; ++vi) {
+                Q.push(*vi);
+            }
+            return core_numbers_impl(g, c, wm, Q);
+        }
+
+        // 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 property_traits<CoreMap>::value_type
+        core_numbers_impl(Graph& g, CoreMap c, PositionMap pos)
+        {
+            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 (tie(vi,vi_end) = vertices(g); vi!=vi_end; ++vi) {
+                max_deg = (std::max)(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 (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 (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];
+                v_cn = get(c,v);
+                typename graph_traits<Graph>::out_edge_iterator oi,oi_end;
+                for (tie(oi,oi_end) = out_edges(v,g); oi!=oi_end; ++oi) {
+                    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);
+                    }
+                }
+            }
+            return v_cn;
+        }
+
+    } // namespace detail
+
+    template <typename Graph, typename CoreMap>
+    typename property_traits<CoreMap>::value_type
+    core_numbers(Graph& g, CoreMap c)
+    {
+        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))
+        );
+    }
+
+    template <typename Graph, typename CoreMap, typename EdgeWeightMap,
+        typename VertexIndexMap >
+    typename property_traits<CoreMap>::value_type
+    core_numbers(Graph& g, CoreMap c, EdgeWeightMap wm, VertexIndexMap vim)
+    {
+        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);
+    }
+
+    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));
+    }
+
+    template <typename Graph, typename CoreMap>
+    typename property_traits<CoreMap>::value_type
+    weighted_core_numbers(Graph& g, CoreMap c)
+    {
+        return core_numbers(g,c,get(edge_weight,g));
+    }
+
+} // namespace boost
+
+#endif // BOOST_GRAPH_CORE_NUMBERS_HPP
+