Re: [jgrapht-developers] obtaining neighbor sets

[John V. S. <js...@gm...>]

See CrossComponentIterator.createGraphSpecifics.  It uses (g instanceof
DirectedGraph) to decide whether to use outgoingEdgeOf or edgesOf during
traversals.

So you're correct regarding interactions through the Graph interface,
but DirectedGraph and UndirectedGraph are also significant interfaces in
JGraphT.

JVS  "And who is my neighbor?"

On Tue, 2005-12-13 at 21:51 -0500, Charles Fry wrote:
> 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
> > 
> > 
>