Re: [jgrapht-users] Mixed graphs

[Rushang K. <rus...@ho...>]

Hi,
 
The solution proposed by Dimitris could tax your memory if the graph was large. However it is the most easiest solution to implement.
 
What algorithms do you want to run on the graph? Perhaps then it would be more clearer for us to help you.
 
If you are going to develop some of your own algorithms (that suit your problem) let us know those too.
 
Date: Fri, 9 Jan 2015 19:38:05 +0200
From: dma...@cs...
To: mat...@gm...
CC: jgr...@li...
Subject: Re: [jgrapht-users] Mixed graphs


  
    
  
  
    I 'm entirely sure that the formulation of your problem requires
    that both directed and undirected edges have to exist in the same
    graph. However, sometimes, whenever there is such a requirement, it
    is advisable to go back to the problem and consider whether its
    model really requires both kinds of edges. 

    

    If, after reconsidering the problem, it is still absolutely
    necessary to have both kind of edges, consider whether the
    operations you perform on the graph require both kinds of edges. If
    they do, you could built two different graphs (1 directed, 1
    undirected) with the same set of nodes, but a different set of edges
    and adapt your operations to check both graphs. 

    

    Hope that helps a bit.

    

    

    

    On 08/01/2015 01:41 μμ, Matyas Krutsky
      wrote:

    
    
      Thank you for your response, but unfortunately this
        is not applicable for me since I have to distinguish between
        cases where there are actually two directed edges with opposite
        direction between two nodes and where there is an undirected
        edge. I would have to keep track of undirected edges somewhere
        and treat both directed edges which forms the undirected edge as
        one when changing some property or removing the edge. This seems
        more difficult and error-prone then creating a sort of
        "semidirected view" over undirected graph as I suggested... 
      

        2015-01-08 12:26 GMT+01:00 Dimitris
          Mavroeidis <dma...@cs...>:

          This is a
            more general answer and applies to any graph implementation.
            It is often used in situations such as the one you describe.

            

            You can use a directed graph and simply represent any
            undirected edge with two directed edges. So, if you have an
            undirected edge between node A and node B, you would create
            an edge from node A to node B and another from node B to
            node A.

            

            If you think of it, an undirected graph is a generalization
            of a directed graph containing both directions between
            nodes.

            

            Dimitris

            

            On 08/01/2015 11:50 πμ, krutor wrote:

            
              Hi, I'm considering using JGraphT as general graphstore in
              my project, but I

              need to represent graph as Mixed graph

              (http://mathworld.wolfram.com/MixedGraph.html)
              - using directed and

              undirected edges together in  one graph. Is there any way
              to simulate this

              behaviour in JGraphT?

              

              The best I came up with yet, is to hide JGraphT behind my
              own interface, use

              custom edges with DIRECTED flag and undirected graph
              implementation

              overriding methods behavior where needed. When using
              algorithms, it is

              usually ok for me that graph is treated like undirected,
              so I will just use

              them with the underlying undirected graph...

              

              Cleaner implementation may be implementing my own

              AbstractBaseGraph.Specifics, but that is impossible to do
              since Specifics

              class is private. Is there any special reason for it to be
              private?

              

              Is there any better way to do it? Am I missing something
              important?

              

              Thanks for response

              

              

              

              

              --

              View this message in context: http://jgrapht-users.107614.n3.nabble.com/Mixed-graphs-tp4024952.html

              Sent from the jgrapht-users mailing list archive at
              Nabble.com.

              

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