Re: [jgrapht-users] get all vertices of a certain type

[Joris K. <de...@gm...>]

Dear Alex,

I'm doing something similar in my code. I'll show you what I did

1. I created a class Vertex, and two subclasses 'Student' and 'Stop',
which both extend the class Vertex.
2. Next I created a class SBRGraph which extends
ListenableUndirectedWeightedGraph<Vertex,DefaultWeightedEdge>
3. I wrote the following method:

public <T extends Vertex> Set<T> getNeighbors(Vertex v, Class<T> vType){
  if(!this.containsVertex(v))
    return Collections.emptySet();
  else{
    Set<DefaultWeightedEdge> incidentEdges=this.edgesOf(v);
    Set<T> neighbors=new HashSet<T>();
    for(DefaultWeightedEdge e: incidentEdges){
      Vertex neighbor=(this.getEdgeTarget(e)!=v ?
this.getEdgeTarget(e) : this.getEdgeSource(e));
      if(neighbor.getClass() == vType)
        neighbors.add(vType.cast(neighbor));
      }
        return neighbors;
    }
}

This method allows me to query neighbors of a given type. Let's say
that I want to find all neighbors of the type Student for a given
vertex v in the graph, then I would invoke:
graph.getNeighbors(v,Student.class). The result would be an
ArrayList<Student>.
Obviously, if you just want to query the list of vertices of a given
type, the easiest thing is to extend the addVertex() method in the
graph and maintain lists of vertices of a specific type.

br,

Joris


On Wed, Oct 17, 2012 at 4:03 AM, Alex Moir
<am...@di...> wrote:
> I am new to jgrapht.  If I create a custom Vertex class that is abstract and
> it has two sub classes, is there an easy way to get all the vertices of only
> one of the subclass types?
>
>
>
> For example, if my custom vertex type is MyGenericVertex, and one subclass
> is HumanVertex and the other is ComputerVertex.  Is there a built in way to
> efficiently get all the HumanVertex objects?
>
>
>
> I tried searching the archives for an answer to this and didn’t see one .
> The closest thing I found was this topic:
>
> http://sourceforge.net/mailarchive/message.php?msg_id=22046693
>
>
>
> Do I have to maintain my own data structures, one for HumanVertex and one
> for ComputerVertex?
>
>
>
> Thanks,
>
> Alex
>
>
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