Hi Justin,
thanks for the clarification, that makes it clear now. Indeed, that is how I create my graph, using a LineGraphGenerator passed to a FeatureGraphGenerator.
Thanks for the help!

Martin

On 9/1/2010 7:02 PM, Justin Deoliveira wrote:


On Wed, Sep 1, 2010 at 11:41 AM, Martin Tomko <[email protected] <mailto:[email protected]>> wrote:

    Dear Justin,
    thanks, that's exactly what I needed - I know that the JTS
    geometry will be in whatever the native units are , that's fine
    with me.
    Would it be possible to update the javadoc to say tha the Object
    is actually the geometry? I was suspecting that, but was not sure
    whether it is the original feature or the geometry.


Well the object depends on how the graph was built, and what the nodes and edges in the graph are modelling. But yeah, could probably use an example right in the javadoc.


    Is there any equivalent method to get back to the generating
    feature (so that one could get some of the other attributes, maybe
    containing other values for weights?)


Again it depends on how you built the graph. What I suggest you do is build your graph using a FeatureGraphGenerator that gets passed a LineGraphGenerator. This will create graph the same way but the edge objects will be the features themselves. And you can access them accordingly.


    Thanks
    Martin


    On 9/1/2010 5:20 PM, Justin Deoliveira wrote:
    Hi Martin,

    Yeah you should be able to get at the underlying LineString by
    calling e.getObject(). Something like:

    DijkstraIterator.EdgeWeigter weighter =new
     DijkstraIterator.EdgeWeighter() {
       public  double  getWeight(Edge e) {
          LineString l = (LineString) e.getObject();
          return l.getLength();
       }
    }

    However the linestring has no notion of units. That will depend
    on whatever coordinate system your data is in.

    On Wed, Sep 1, 2010 at 10:55 AM, Martin Tomko
    <[email protected] <mailto:[email protected]>> wrote:

        Dear All,
        I am using the Graph api to construct a graph based on
        lineStrings -
        that works perfectly. I would like to do a shortest path
        computation
        based on geographical distance, and need to implement a Weighter.

        the docs show this snippet:

        DijkstraIterator.EdgeWeigter weighter =new
         DijkstraIterator.EdgeWeighter() {
           public  double  getWeight(Edge e) {
              return  1.0;//constant
           }
        }

        which results in a constant weight for an edge of 1.

        How do I get the actual length of an edge, in the original
        feature's units...

        I need the values also for other purposes, so really neend to
        access the edge length property.
        Is it possible?
        Thanks
        Martin



        
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-- Justin Deoliveira
    OpenGeo - http://opengeo.org
    Enterprise support for open source geospatial.



-- Martin Tomko
    Postdoctoral Research Assistant

    Geographic Information Systems Division
    Department of Geography
    University of Zurich - Irchel
    Winterthurerstr. 190
    CH-8057 Zurich, Switzerland

    email:      [email protected]  <mailto:[email protected]>
    site:       http://www.geo.uzh.ch/~mtomko  <http://www.geo.uzh.ch/%7Emtomko>
    mob:        +41-788 629 558
    tel:        +41-44-6355256
    fax:        +41-44-6356848




--
Justin Deoliveira
OpenGeo - http://opengeo.org
Enterprise support for open source geospatial.



--
Martin Tomko
Postdoctoral Research Assistant

Geographic Information Systems Division
Department of Geography
University of Zurich - Irchel
Winterthurerstr. 190
CH-8057 Zurich, Switzerland

email:  [email protected]
site:   http://www.geo.uzh.ch/~mtomko
mob:    +41-788 629 558
tel:    +41-44-6355256
fax:    +41-44-6356848

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