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<div>Ah! I didn't look closely at the DIMACS file specs at <a href="http://www.dis.uniroma1.it/~challenge9/format.shtml#graph">http://www.dis.uniroma1.it/~challenge9/format.shtml#graph</a>:</div>
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<div><img src="http://www.dis.uniroma1.it/%7Echallenge9/images/bullet-orange.gif" height="10" width="8"> A graph contains
<i>n </i>nodes and <i>m </i>arcs<br>
<b><img src="http://www.dis.uniroma1.it/%7Echallenge9/images/bullet-orange.gif" height="10" width="8"> Nodes are identified by integers 1...</b><i><b>n</b></i><br>
<img src="http://www.dis.uniroma1.it/%7Echallenge9/images/bullet-orange.gif" height="10" width="8"> Graphs can be interpreted as directed or undirected, depending on the problem being studied<br>
<img src="http://www.dis.uniroma1.it/%7Echallenge9/images/bullet-orange.gif" height="10" width="8"> Graphs can have parallel arcs and self-loops<br>
<img src="http://www.dis.uniroma1.it/%7Echallenge9/images/bullet-orange.gif" height="10" width="8"> Arc weights are signed integers</div>
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<div>It looks like the writer is happily writing out files with vertices from 0..n-1 rather than 1..n. </div>
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<div>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...</div>
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<div>Thanks for providing a few extra pairs of eyeballs... :D</div>
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<div>-William</div>
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<span style="font-weight:bold">From: </span>"Eric E. Monson" <<a href="mailto:emonson@cs.duke.edu">emonson@cs.duke.edu</a>><br>
<span style="font-weight:bold">Date: </span>Wed, 22 Jun 2011 14:52:34 -0400<br>
<span style="font-weight:bold">To: </span>William C McLendon <<a href="mailto:wcmclen@sandia.gov">wcmclen@sandia.gov</a>><br>
<span style="font-weight:bold">Cc: </span>"<a href="mailto:vtk-developers@vtk.org">vtk-developers@vtk.org</a> Developers" <<a href="mailto:vtk-developers@vtk.org">vtk-developers@vtk.org</a>><br>
<span style="font-weight:bold">Subject: </span>Re: [vtk-developers] vtkDIMACS reader/writer bug<br>
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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.
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<div>-Eric</div>
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<div>On Jun 22, 2011, at 2:46 PM, Eric E. Monson wrote:</div>
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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.
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<div>-Eric</div>
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<div>On Jun 22, 2011, at 1:47 PM, Mclendon, William C III wrote:</div>
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<div>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.</div>
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<div>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.</div>
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<div>-William</div>
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