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I'm using Boost library to work with graphs in C++. 

boost::adjacency_list <boost::vecS, boost::vecS, boost::bidirectionalS> DiGraph;
DiGraph graph;
boost::add_edge(10000, 20000, graph);

The graph contains 20001 vertices and one edge. Yet, I need to have only two vertices 10000 and 20000.

One possible way is to associate data with nodes (e.g. from this example); however, maybe there is a simpler way to do this. How can I have a graph with 2 vertices and one edge, if the vertices are not (0,1)?

In python networkx I would use simply graph.add_edge(10000, 20000) and would get desired behavior. Any clues how to do this in C++?

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Sergey Ivanov
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  • The default behavior is indeed to have indexes identify vertices. So, true, if you only create an edge between vertices 10 and 20, then the graph will hold 21 vertices. What you need is a model of a vertices with a free identifier, so, yes, study the linked example, it holds what you need. The good point is that you can stuff anything you want in vertices. – kebs Dec 01 '15 at 12:40
  • Well, I do prefer to avoid this somehow. – Sergey Ivanov Dec 01 '15 at 12:41

1 Answers1

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You should use a node-based container selector for the vertex collection.

E.g. using listS:

#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/graph_utility.hpp>

int main() {
    typedef boost::adjacency_list <boost::vecS, boost::listS, boost::bidirectionalS, int> DiGraph;
    DiGraph graph;

    DiGraph::vertex_descriptor 
        v1 = add_vertex(100000, graph),
        v2 = add_vertex(200000, graph);

    boost::add_edge(v1, v2, graph);
    boost::print_graph(graph, boost::get(boost::vertex_bundle, graph));
}

Note that vertex_index doesn't come for free now (you have to pass/maintain it manually for all algorithms).

On the up-side, iterators and descriptors are stable (unless deleted).

sehe
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