Re: [jgrapht-developers] obtaining neighbor sets

[Charles F. <cf...@us...>]

Another question: Why is AsUndirectedGraph important? I see that
ConnectivityInspector uses it to obtain an undirected view of a directed
graph. As far as I can tell, the only practical implication of this is
that it provides degreeOf, which doesn't exist for DirectedGraphs. But
as far as I can tell, a DirectedGraph interacted with through the Graph
interface will be indistinguishable from an UndirectedGraph. Am I
missing something here?

thanks,
Charles

-----Original Message-----
> From: "John V. Sichi" <js...@gm...>
> Subject: Re: [jgrapht-developers] obtaining neighbor sets
> Date: Mon, 12 Dec 2005 22:20:40 -0800
> To: Charles Fry <cf...@us...>
> Cc: jgr...@li...
> 
> On Mon, 2005-12-12 at 14:37 -0500, Charles Fry wrote:
> > John suggested that this be implemented as a GraphListener. I thought it
> > could be named NeighborListener or something like that. The static
> 
> Perhaps org._3pq.jgrapht.alg.NeighborIndex, since the listening part is
> just an implementation detail; the purpose is to maintain an efficient
> index structure for answering queries.
> 
> > method could match that from GraphHelper except that for efficiency I
> > would have liked it to return a Set instead of a List:
> > 
> >    Set neighborListOf(Graph g, Object vertex);
> 
> So neighborsOf instead of neighborListOf, right?
> 
> Be careful about the multigraph case, where removing an edge doesn't
> necessarily imply removing a neighbor.
> 
> > Would I want two different classes, one for undirected graphs, and one
> > for directed graphs (predecessorListOf and successorListOf)?
> 
> For ConnectivityInspector, what we did was:
> 
> - ConnectivityInspector calculates connectivity information without
> regard for edge direction; so if you give it a directed graph, it
> inspects an undirected view
> 
> - StrongConnectivityInspector calculates connectivity information taking
> edge direction into account; you can't give it an undirected graph
> 
> So in your case, maybe NeighborIndex and DirectedNeighborIndex?
> 
> JVS
> 
> 

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