Re: [jgrapht-users] Edge weights

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

As the exception states, you are adding an edge to your graph which results
in a loop which is not permitted for the type of graph you are currently
working with. Consider using a DirectedPseudograph
<http://mathworld.wolfram.com/Pseudograph.html>.

​Regards,​

Besenyei Szabolcs

2015-07-02 17:15 GMT+02:00 fee...@gm... <fee...@gm...>:

> Thank you guys for your replies… I’ve made some changes in my simple code
> taking into account your advice…..however I’m still getting this error:
>
> Exception in thread "main" java.lang.IllegalArgumentException: loops not
> allowed
> ÏÏ§Ï        at
> org.jgrapht.graph.AbstractBaseGraph.addEdge(AbstractBaseGraph.java:243)
> ÏÏ§Ï        at org.jgrapht.Graphs.addEdge(Graphs.java:88)
> ÏÏ§Ï        at JGraphTestDirected.main(JGraphTestDirected.java:77)
>
>
> My plan is simple…take a matrix with weights…….two for loops to go through
> it for creating edges and adding weights.
>
>
> any help will be appreciated.
>
>
> Phil
>
>
>
> On 1/07/2015, at 7:26 pm, Joris Kinable <de...@gm...> wrote:
>
> Three ways to add weighted edges:
>
> 1. Use the graph itself:
> DefaultWeightedEdge e=graph.addEdge(V vertex1, V vertex2);
> graph.setEdgeWeight(e, double weight);
>
> 2. Use one of the following methods in the Graphs package:
> Graphs.addAllEdges(Graph<? super V,? super E> destination, Graph<V,E>
> source, Collection<? extends E> edges)
> Graphs.addEdge(Graph<V,E> g, V sourceVertex, V targetVertex, double weight)
> Graphs.addEdgeWithVertices(Graph<V,E> targetGraph, Graph<V,E> sourceGraph,
> E edge, double weight)
>
> 3. Use the Graph Builder which was added to the latest version of jgrapht:
> SimpleWeightedGraph<String, DefaultWeightedEdge> builtWeightedGraph =
>         SimpleWeightedGraph.<String, DefaultWeightedEdge>
>         builder(DefaultWeightedEdge.class)
>         .addEdge(v1, v2, 1.0)
>         .addEdge(v1, v2, 2.0)
>         .addEdge(v3, v4, 3.0)
>         .addEdge(v2, v4, 2.0)
>         .build();
>
>
> br,
>
> Joris Kinable
>
> On Wed, Jul 1, 2015 at 7:13 PM, Rushang Karia <rus...@ho...>
> wrote:
>
>> I am at work right now and do not remember if such a function exists (not
>> worked on weighted graphs a lot). I guess there should be such a function
>> since your problem is quite intuitive.
>>
>> However,
>> If no such function exists then you could overload the addEdge() to
>> specify a weight for the WeightedGraph.
>> The function would be
>>
>> DefaultWeightedEdge  <V, E> addEdge(V v1, V v2, E weight)
>> {
>>         DefaultWeightedEdge e1 = super.addEdge(v1, v2);
>>         this.setEdgeWeight(e1, weight)
>>         If(error) return null else return the edge.
>> }
>>
>> I am sorry if my reply is brief but I am a bit busy right now. If you
>> need more detailed instructions feel free to reply.
>>
>> -----Original Message-----
>> From: fee...@gm... [mailto:fee...@gm...]
>> Sent: Wednesday, July 01, 2015 4:05 PM
>> To: jgr...@li...
>> Subject: [jgrapht-users] Edge weights
>>
>> Hi there,
>>
>> I’m a newbie using Jgrapht… .My problem  has to do with a large weighted
>> graph (about 2000 edges)   and the assignation of its weights.
>>
>> All I wanna ask is whether or not weights for a graph can be assigned
>> dynamically  (a loop) rather than static (one by on)...like:
>>
>> DefaultWeightedEdge e1 = graph.addEdge("vertex1", "vertex2”);
>> graph.setEdgeWeight(e1, 5);
>>
>> (I’d have to write this thousand times…. )
>>
>>
>> Thanks.
>>
>> Phil
>>
>>
>>
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