Re: [jgrapht-users] Label Edge Example

[Szabolcs B. <bes...@gm...>]

Hi!

The problem here is that DirectedMultigraph doest not allow loops and in
your first loop you are trying to do

> graph.addEdge(people.get(0), person, new
> RelationshipEdge<String>(people.get(0), person, friend));
>
which translates to

> graph.addEdge("John", "John", new RelationshipEdge<String>("John", "John",
> friend)); on the first iteration.
>

Your option here is to either use a DefaultDirectedGraph (a non-simple
directed graph in which multiple edges between any two vertices are
*not*permitted, but loops are) or rewrite your code so that it does
not try to
friend John with "himself".



2014-03-15 16:18 GMT+01:00 Patricia_Sim <pt...@gm...>:

> Hi Everybody
>
> I'm trying to create directed graph with label edge by jgrapht. I learn how
> to create by "LabeledEdges" example which source code shown below
>
> public class LabeledEdges {
>     private static final String friend = "friend";
>     private static final String enemy = "enemy";
>
>     public static void main(String[] args) {
>         DirectedGraph<String, RelationshipEdge> graph =
>             new DirectedMultigraph<String, RelationshipEdge>(
>                     new ClassBasedEdgeFactory<String,
> RelationshipEdge>(RelationshipEdge.class));
>
>         ArrayList<String> people = new ArrayList<String>();
>         people.add("John");
>         people.add("James");
>         people.add("Sarah");
>         people.add("Jessica");
>
>         // John is everyone's friend
>         for (String person : people) {
>             graph.addVertex(person);
>             graph.addEdge(people.get(0), person, new
> RelationshipEdge<String>(people.get(0), person, friend));
>         }
>
>         // Apparently James doesn't really like John
>         graph.addEdge("James", "John", new
> RelationshipEdge<String>("James",
> "John", enemy));
>
>         // Jessica is Sarah and James's friend
>         graph.addEdge("Jessica", "Sarah", new
> RelationshipEdge<String>("Jessica", "Sarah", friend));
>         graph.addEdge("Jessica", "James", new
> RelationshipEdge<String>("Jessica", "James", friend));
>
>         // But Sarah doesn't really like James
>         graph.addEdge("Sarah", "James", new
> RelationshipEdge<String>("Sarah", "James", enemy));
>
>          for (RelationshipEdge edge : graph.edgeSet()) {
>         if (edge.toString().equals("enemy")) {
>             System.out.printf(edge.getV1()+"is an enemy of "+
> edge.getV2()+"\n");
>         } else if (edge.toString().equals("friend")) {
>             System.out.printf( edge.getV1()+" is a friend of "+
> edge.getV2()+"\n");
>         }
>     }
>     }
>
>     public static class RelationshipEdge<V> extends DefaultEdge {
>         private V v1;
>         private V v2;
>         private String label;
>
>         public RelationshipEdge(V v1, V v2, String label) {
>             this.v1 = v1;
>             this.v2 = v2;
>             this.label = label;
>         }
>
>         public V getV1() {
>             return v1;
>         }
>
>         public V getV2() {
>             return v2;
>         }
>
>         public String toString() {
>             return label;
>         }
>     }
>
> However, when I run this example, it show the error message
>         "Exception in thread "main" java.lang.IllegalArgumentException:
> loops not allowed
>         at
> org.jgrapht.graph.AbstractBaseGraph.addEdge(AbstractBaseGraph.java:243)"
>
> How can I do to run this example
>
>
>
> --
> View this message in context:
> http://jgrapht-users.107614.n3.nabble.com/Label-Edge-Example-tp4024899.html
> Sent from the jgrapht-users mailing list archive at Nabble.com.
>
>
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