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Thickness (weight) in dynamic graph

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Thickness (weight) in dynamic graph

Postby EugeneR » 03 Oct 2013 11:47

Would someone explain me why in my simple case (file attached) the weight of edge doesn't change through the time line.
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<?xml version="1.0" encoding="UTF-8"?>
<gexf xmlns="http://www.gexf.net/1.2draft" version="1.2" xmlns:viz="http://www.gexf.net/1.2draft/viz" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.gexf.net/1.2draft http://www.gexf.net/1.2draft/gexf.xsd">
  <meta lastmodifieddate="2013-10-03">
    <creator>Gephi 0.8.1</creator>
    <description></description>
  </meta>
  <graph defaultedgetype="directed" timeformat="double" mode="dynamic">
    <attributes class="node" mode="dynamic">
      <attribute id="score" title="score" type="integer"></attribute>
    </attributes>
    <attributes class="edge" mode="dynamic">
      <attribute id="weight" title="Weight" type="float"></attribute>
    </attributes>
    <nodes>
      <node id="n0" label="n0" start="2005.0" end="2034.0">
      </node>
      <node id="n5" label="n5" start="2005.0" end="2034.0">
      </node>
    </nodes>
    <edges>
      <edge source="n0" target="n5">
        <attvalues>
          <attvalue for="weight" value="1.0" start="2010.0" endopen="2012.0"></attvalue>
          <attvalue for="weight" value="4.0" start="2012.0" endopen="2014.0"></attvalue>
          <attvalue for="weight" value="3.0" start="2014.0" endopen="2016.0"></attvalue>
          <attvalue for="weight" value="4.0" start="2016.0" endopen="2018.0"></attvalue>
          <attvalue for="weight" value="7.0" start="2018.0" endopen="2020.0"></attvalue>
          <attvalue for="weight" value="6.0" start="2020.0" endopen="2022.0"></attvalue>
          <attvalue for="weight" value="9.0" start="2022.0" endopen="2024.0"></attvalue>
          <attvalue for="weight" value="20.0" start="2024.0" end="2026.0"></attvalue>
        </attvalues>
      </edge>
    </edges>
  </graph>
</gexf>
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EugeneR
 
Posts: 5
Joined: 12 Sep 2013 15:18

Re: Thickness (weight) in dynamic graph

Postby seinecle » 04 Oct 2013 19:42

Hi,

Interesting issue, thanks for posting about that. I attach a modified version of your gexf: I added a 3rd node and a 2nd edge. This second edge has decreasing weights with time, while the 1st edge in your original file had increasing weight with time. The value of the weight for the 2 edges crosses (is equal) when the date is 2020.

Before 2020: 1st edge is thin, 2nd edge is thick. No evolution until 2020.
At 2020: both edges equally thin (as said above they have the same weight value at this date)
After 2020: 1st edge is thick, 2nd edge is thin. No evolution until the end of the timeline.

This suggests that the thickness of edges is established relatively between edges.
-> With just one edge on the graph: no comparison to be made. Even if the weight of this edge varies, its thickness will remain constant because there is no other edge to compare it to.
-> several edges on the graph: at each point in time, Gephi checks all weights of all edges at this point in time. It establishes a range of thickness function of the lowest to the highest weight values at this point in time.

You can have a finer grained view on the evolution of the values of the weight of individual edges by using a dynamic ranking on edge's weight (in the ranking panel, select edges, click on the tiny icon just left to "Auto Apply", then click on Auto apply. Then run the timeline.) You should see the edge' color vary according to weight's values.

This applies to the edge' color or label size though, not edge thickness. Here, even with just one edge on your graph, you'd see its color change with time.

My view? This could definitely be improved, maybe by simply treating the edge thickness as any other visual attribute (like edge color or label size, which can be controlled from the ranking panel). I open an issue on Github:
https://github.com/gephi/gephi/issues/836

Best,

Clement
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2.gexf
(3.69 KiB) Downloaded 46 times
http://www.clementlevallois.net
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Re: Thicknes (weight) in dynamic graph

Postby EugeneR » 08 Oct 2013 11:23

Many thanks for Your comment! I didn't really know that GePhi depict relative size of edges not absolute. I think You are absolutely right concerning forthcoming improvements in this direction. The only thing I would also know is how difficult to make such kind of improvement?
EugeneR
 
Posts: 5
Joined: 12 Sep 2013 15:18

Re: Thickness (weight) in dynamic graph

Postby seinecle » 08 Oct 2013 11:45

This is not trivial, since this touches to the visual rendering in the overview mode. I think core developers would need to do this, not plugin developers.
http://www.clementlevallois.net
Gephi tutorials and personalized trainings: http://www.clementlevallois.net/training.html
Join the Gephi Facebook group for help and support: https://www.facebook.com/groups/gephi/
User avatar
seinecle
Gephi Community Support
 
Posts: 539
Joined: 08 Feb 2010 17:55
Location: Lyon, France


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