Oct 31, 2010 at 8:41 PM
Edited Oct 31, 2010 at 9:31 PM

Hi,
I'm just getting started with the library and I'm trying to figure out how to use it "the right way". For example, I needed a function that returns the neighborhood of a vertex, much like this one:
http://igraph.sourceforge.net/doc/R/neighborhood.html
I was a bit surprised that such a function isn't already included, but it gave me a good chance to start learning the library. Here is what I came up with:
public static class NeighborhoodExtension
{
private static void NeighborhoodHelper<TVertex, TEdge>(IVertexListGraph<TVertex, TEdge> graph, int order, TVertex vertex, EdgeFactory<TVertex, TEdge> edgeFactory, IMutableVertexAndEdgeListGraph<TVertex, TEdge> result)
where TEdge : IEdge<TVertex>
{
if(result.AddVertex(vertex))
{
if (order > 0)
{
foreach (var edge in graph.OutEdges(vertex))
{
NeighborhoodHelper(graph, order  1, edge.Target, edgeFactory, result);
result.AddEdge(edgeFactory(vertex, edge.Target));
}
}
}
}
public static IVertexAndEdgeListGraph<TVertex, TEdge> Neighborhood<TVertex, TEdge>(this IVertexListGraph<TVertex, TEdge> graph, int order, TVertex vertex, EdgeFactory<TVertex, TEdge> edgeFactory)
where TEdge : IEdge<TVertex>
{
var result = new AdjacencyGraph<TVertex, TEdge>();
NeighborhoodHelper(graph, order, vertex, edgeFactory, result);
return result;
}
}
It would be very helpful to receive some input by more experienced users. I'm sure there are many ways this code could be improved.
I'm looking forward to your comments!

