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// (C) Copyright Andrew Sutton 2007
//
// 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)
//[mean_geodesic_example
#include <iostream>
#include <iomanip>
#include <boost/graph/undirected_graph.hpp>
#include <boost/graph/exterior_property.hpp>
#include <boost/graph/floyd_warshall_shortest.hpp>
#include <boost/graph/geodesic_distance.hpp>
#include "helper.hpp"
using namespace std;
using namespace boost;
// The Actor type stores the name of each vertex in the graph.
struct Actor
{
string name;
};
// Declare the graph type and its vertex and edge types.
typedef undirected_graph< Actor > Graph;
typedef graph_traits< Graph >::vertex_descriptor Vertex;
typedef graph_traits< Graph >::edge_descriptor Edge;
// The name map provides an abstract accessor for the names of
// each vertex. This is used during graph creation.
typedef property_map< Graph, string Actor::* >::type NameMap;
// Declare a matrix type and its corresponding property map that
// will contain the distances between each pair of vertices.
typedef exterior_vertex_property< Graph, int > DistanceProperty;
typedef DistanceProperty::matrix_type DistanceMatrix;
typedef DistanceProperty::matrix_map_type DistanceMatrixMap;
// Declare the weight map so that each edge returns the same value.
typedef constant_property_map< Edge, int > WeightMap;
// Declare a container and its corresponding property map that
// will contain the resulting mean geodesic distances of each
// vertex in the graph.
typedef exterior_vertex_property< Graph, float > GeodesicProperty;
typedef GeodesicProperty::container_type GeodesicContainer;
typedef GeodesicProperty::map_type GeodesicMap;
int main(int argc, char* argv[])
{
// Create the graph and a property map that provides access
// to the actor names.
Graph g;
NameMap nm(get(&Actor::name, g));
// Read the graph from standad input.
read_graph(g, nm, cin);
// Compute the distances between all pairs of vertices using
// the Floyd-Warshall algorithm. Note that the weight map is
// created so that every edge has a weight of 1.
DistanceMatrix distances(num_vertices(g));
DistanceMatrixMap dm(distances, g);
WeightMap wm(1);
floyd_warshall_all_pairs_shortest_paths(g, dm, weight_map(wm));
// Compute the mean geodesic distances for each vertex in
// the graph and get the average mean geodesic distace (the
// so-called small-world distance) as a result.
GeodesicContainer geodesics(num_vertices(g));
GeodesicMap gm(geodesics, g);
float sw = all_mean_geodesics(g, dm, gm);
// Print the mean geodesic distance of each vertex and finally,
// the graph itself.
graph_traits< Graph >::vertex_iterator i, end;
for (boost::tie(i, end) = vertices(g); i != end; ++i)
{
cout << setw(12) << setiosflags(ios::left) << g[*i].name << get(gm, *i)
<< endl;
}
cout << "small world distance: " << sw << endl;
return 0;
}
//]
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