Added boost header

test/external/boost/graph/clustering_coefficient.hpp

@@ -0,0 +1,158 @@
+// (C) Copyright 2007-2009 Andrew Sutton
+//
+// Use, modification and distribution are subject to the
+// Boost Software License, Version 1.0 (See accompanying file
+// LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_GRAPH_CLUSTERING_COEFFICIENT_HPP
+#define BOOST_GRAPH_CLUSTERING_COEFFICIENT_HPP
+
+#include <boost/utility.hpp>
+#include <boost/graph/graph_traits.hpp>
+#include <boost/graph/graph_concepts.hpp>
+#include <boost/graph/lookup_edge.hpp>
+
+namespace boost
+{
+namespace detail
+{
+    template <class Graph>
+    inline typename graph_traits<Graph>::degree_size_type
+    possible_edges(const Graph& g, std::size_t k, directed_tag)
+    {
+        function_requires< GraphConcept<Graph> >();
+        typedef typename graph_traits<Graph>::degree_size_type T;
+        return T(k) * (T(k) - 1);
+    }
+
+    template <class Graph>
+    inline typename graph_traits<Graph>::degree_size_type
+    possible_edges(const Graph& g, size_t k, undirected_tag)
+    {
+        // dirty little trick...
+        return possible_edges(g, k, directed_tag()) / 2;
+    }
+
+    // This template matches directedS and bidirectionalS.
+    template <class Graph>
+    inline typename graph_traits<Graph>::degree_size_type
+    count_edges(const Graph& g,
+                typename graph_traits<Graph>::vertex_descriptor u,
+                typename graph_traits<Graph>::vertex_descriptor v,
+                directed_tag)
+
+    {
+        function_requires< AdjacencyMatrixConcept<Graph> >();
+        return (lookup_edge(u, v, g).second ? 1 : 0) +
+                (lookup_edge(v, u, g).second ? 1 : 0);
+    }
+
+    // This template matches undirectedS
+    template <class Graph>
+    inline typename graph_traits<Graph>::degree_size_type
+    count_edges(const Graph& g,
+                typename graph_traits<Graph>::vertex_descriptor u,
+                typename graph_traits<Graph>::vertex_descriptor v,
+                undirected_tag)
+    {
+        function_requires< AdjacencyMatrixConcept<Graph> >();
+        return lookup_edge(u, v, g).second ? 1 : 0;
+    }
+}
+
+template <typename Graph, typename Vertex>
+inline typename graph_traits<Graph>::degree_size_type
+num_paths_through_vertex(const Graph& g, Vertex v)
+{
+    function_requires< AdjacencyGraphConcept<Graph> >();
+    typedef typename graph_traits<Graph>::directed_category Directed;
+    typedef typename graph_traits<Graph>::adjacency_iterator AdjacencyIterator;
+
+    // TODO: There should actually be a set of neighborhood functions
+    // for things like this (num_neighbors() would be great).
+
+    AdjacencyIterator i, end;
+    boost::tie(i, end) = adjacent_vertices(v, g);
+    std::size_t k = std::distance(i, end);
+    return detail::possible_edges(g, k, Directed());
+}
+
+template <typename Graph, typename Vertex>
+inline typename graph_traits<Graph>::degree_size_type
+num_triangles_on_vertex(const Graph& g, Vertex v)
+{
+    function_requires< IncidenceGraphConcept<Graph> >();
+    function_requires< AdjacencyGraphConcept<Graph> >();
+    typedef typename graph_traits<Graph>::degree_size_type Degree;
+    typedef typename graph_traits<Graph>::directed_category Directed;
+    typedef typename graph_traits<Graph>::adjacency_iterator AdjacencyIterator;
+
+    // TODO: I might be able to reduce the requirement from adjacency graph
+    // to incidence graph by using out edges.
+
+    Degree count(0);
+    AdjacencyIterator i, j, end;
+    for(boost::tie(i, end) = adjacent_vertices(v, g); i != end; ++i) {
+        for(j = boost::next(i); j != end; ++j) {
+            count += detail::count_edges(g, *i, *j, Directed());
+        }
+    }
+    return count;
+} /* namespace detail */
+
+template <typename T, typename Graph, typename Vertex>
+inline T
+clustering_coefficient(const Graph& g, Vertex v)
+{
+    T zero(0);
+    T routes = T(num_paths_through_vertex(g, v));
+    return (routes > zero) ?
+        T(num_triangles_on_vertex(g, v)) / routes : zero;
+}
+
+template <typename Graph, typename Vertex>
+inline double
+clustering_coefficient(const Graph& g, Vertex v)
+{ return clustering_coefficient<double>(g, v); }
+
+template <typename Graph, typename ClusteringMap>
+inline typename property_traits<ClusteringMap>::value_type
+all_clustering_coefficients(const Graph& g, ClusteringMap cm)
+{
+    function_requires< VertexListGraphConcept<Graph> >();
+    typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
+    typedef typename graph_traits<Graph>::vertex_iterator VertexIterator;
+    function_requires< WritablePropertyMapConcept<ClusteringMap,Vertex> >();
+    typedef typename property_traits<ClusteringMap>::value_type Coefficient;
+
+    Coefficient sum(0);
+    VertexIterator i, end;
+    for(boost::tie(i, end) = vertices(g); i != end; ++i) {
+        Coefficient cc = clustering_coefficient<Coefficient>(g, *i);
+        put(cm, *i, cc);
+        sum += cc;
+    }
+    return sum / Coefficient(num_vertices(g));
+}
+
+template <typename Graph, typename ClusteringMap>
+inline typename property_traits<ClusteringMap>::value_type
+mean_clustering_coefficient(const Graph& g, ClusteringMap cm)
+{
+    function_requires< VertexListGraphConcept<Graph> >();
+    typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
+    typedef typename graph_traits<Graph>::vertex_iterator VertexIterator;
+    function_requires< ReadablePropertyMapConcept<ClusteringMap,Vertex> >();
+    typedef typename property_traits<ClusteringMap>::value_type Coefficient;
+
+    Coefficient cc(0);
+    VertexIterator i, end;
+    for(boost::tie(i, end) = vertices(g); i != end; ++i) {
+        cc += get(cm, *i);
+    }
+    return cc / Coefficient(num_vertices(g));
+}
+
+} /* namespace boost */
+
+#endif