[vtk-developers] vtkDIMACS reader/writer bug

Mclendon, William C III wcmclen at sandia.gov
Wed Jun 22 15:15:17 EDT 2011


Ah!  I didn't look closely at the DIMACS file specs at http://www.dis.uniroma1.it/~challenge9/format.shtml#graph:

[http://www.dis.uniroma1.it/%7Echallenge9/images/bullet-orange.gif] A graph contains n nodes and m arcs
[http://www.dis.uniroma1.it/%7Echallenge9/images/bullet-orange.gif] Nodes are identified by integers 1...n
[http://www.dis.uniroma1.it/%7Echallenge9/images/bullet-orange.gif] Graphs can be interpreted as directed or undirected, depending on the problem being studied
[http://www.dis.uniroma1.it/%7Echallenge9/images/bullet-orange.gif] Graphs can have parallel arcs and self-loops
[http://www.dis.uniroma1.it/%7Echallenge9/images/bullet-orange.gif] Arc weights are signed integers

It looks like the writer is happily writing out files with vertices from 0..n-1 rather than 1..n.

I'll toss in a couple checks into the code this afternoon to make the writer generate vertices numbered from 1..n and the reader to add a check to generate a useful warning message if it detects a vertex 0...

Thanks for providing a few extra pairs of eyeballs... :D

-William



From: "Eric E. Monson" <emonson at cs.duke.edu<mailto:emonson at cs.duke.edu>>
Date: Wed, 22 Jun 2011 14:52:34 -0400
To: William C McLendon <wcmclen at sandia.gov<mailto:wcmclen at sandia.gov>>
Cc: "vtk-developers at vtk.org<mailto:vtk-developers at vtk.org> Developers" <vtk-developers at vtk.org<mailto:vtk-developers at vtk.org>>
Subject: Re: [vtk-developers] vtkDIMACS reader/writer bug

Yup, if I add one to the source and target IDs in the writer code, I don't seem to get the crashes any more. Maybe there are other things wrong, too, but that seems to fix it for me.

-Eric


On Jun 22, 2011, at 2:46 PM, Eric E. Monson wrote:

You know, it looks like the graph reader doesn't like node IDs of 0, it likes them to start with 1. If I write out a simpler graph with only 10 nodes, then manually increment each node ID in the file by 1 so they start with 1 instead of 0, it works.

-Eric


On Jun 22, 2011, at 1:47 PM, Mclendon, William C III wrote:

I'm trying to run a script that just generates a random graph and saves it using the DIMACS writer then reads it back using the DIMACS reader.  Unfortunately, when I try to render the graph I get a segfault.

It seems odd since the graphs seem to load properly.  The attached script seems to be crashing for me on both OS-X and under Linux.

-William
<dimacs.py>_______________________________________________
Powered by www.kitware.com<http://www.kitware.com/>

Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

Follow this link to subscribe/unsubscribe:
http://www.vtk.org/mailman/listinfo/vtk-developers


_______________________________________________
Powered by www.kitware.com<http://www.kitware.com>

Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

Follow this link to subscribe/unsubscribe:
http://www.vtk.org/mailman/listinfo/vtk-developers


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtk-developers/attachments/20110622/5e266139/attachment.html>


More information about the vtk-developers mailing list