<p>If you want <em>challenging</em> instances for the vertex cover problem:</p>

<p><a href="http://www.nlsde.buaa.edu.cn/~kexu/benchmarks/graph-benchmarks.htm" rel="nofollow">http://www.nlsde.buaa.edu.cn/~kexu/benchmarks/graph-benchmarks.htm</a></p>

CC BY-SA 3.0
2011-05-17T16:48:16.580Z
2011-05-17T16:48:16.580Z
Jukka Suomela
<p>You can check out the graphs at <a href="http://netwiki.amath.unc.edu/SharedData/SharedData" rel="nofollow">NetWiki</a>.  Of course, you'll have to sort out the formatting yourself.</p>

CC BY-SA 3.0
2011-05-17T11:12:13.593Z
2011-05-17T11:12:13.593Z
James King
<p>Here's a collection of graphs that we used for analyzing a vertex cover heuristic:
<a href="http://www.ru.is/kennarar/eyjo/vertexcover.html" rel="nofollow">http://www.ru.is/kennarar/eyjo/vertexcover.html</a></p>

<p>You can download a zipfile containing all the graphs here:
<a href="http://www.ru.is/kennarar/eyjo/vertexcover/graphs.zip" rel="nofollow">http://www.ru.is/kennarar/eyjo/vertexcover/graphs.zip</a></p>

<p>The format is not exactly as you specified but it's close enough.</p>

CC BY-SA 3.0
2011-05-23T13:45:46.127Z
2011-05-23T13:45:46.127Z
Eyjolfur Ingi Asgeirsson
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="https://cstheory.stackexchange.com/questions/739/data-for-testing-graph-algorithms">Data for testing graph algorithms</a>  </p>
</blockquote>



<p>I recently developed a parallel algorithm to solve the vertex cover problem.<br>
now i need some graphs so i can test the speed of my algorithm vs the sequential code.<br>
where can i find graphs? i am looking for something similar to this text file:  </p>

<pre><code>3 3
1 0
1 2
0 2
</code></pre>

<p>the first 2 numbers (3 and 3) states that there are 3 vertices and 3 edges in the graph. following this line is 3 edges.</p>

CC BY-SA 3.0
2011-05-17T11:15:47.113Z
Hi @scatman: I'm not so sure that your question is within scope, so you may want to try other SE sites as well.
Hsien-Chih Chang 張顯之
CC BY-SA 3.0
2011-05-17T13:03:23.070Z
Check out the answers for the related questions http://cstheory.stackexchange.com/questions/3409/graphs-from-real-life-problems http://cstheory.stackexchange.com/questions/739/data-for-testing-graph-algorithms
Snowie
CC BY-SA 3.0
2011-05-17T13:42:18.050Z
Related MO question [Database of graphs](http://mathoverflow.net/questions/23748/where-on-the-internet-i-can-find-database-of-graphs)
Pratik Deoghare
CC BY-SA 3.0
2011-05-17T15:29:55.743Z
You can also generate random graphs, using packages such as Jung or R or probably any graph library. This would give you some flexibility, as you could vary the kind of graph generated by changing the various parameters available, including the kind of graph.
Dave Clarke
CC BY-SA 3.0
2011-05-17T16:47:13.303Z
(The other question specifically asks for directed graphs, but I think it would be a good idea to slightly edit the question to make it more general, and then merge the answers. Also, it might be a good idea to CW the question.)
Jukka Suomela
CC BY-SA 3.0
2011-05-18T04:34:36.207Z
@Jukka, I have edited the other question (and in fact was going to merge the questions) but then I thought that it might not be a good thing (there is no way to reverse a merge) since this question is asking for graphs for a specific problem. (ps: as result of my closing as duplicate and reopening the question the close votes for this question has been lost. I should have been more careful. Sorry.)
Kaveh
CC BY-SA 3.0
2011-05-18T04:36:25.770Z
Hi scatman, please read the FAQ. Specifying the format of the input is making your question too localized IMO, so I would suggest that edit that part. Also take a look at the question linked above by Jukka to see if the answers for that question would also answer your question (in which case I can merge the questions so all of the answers are in one place). Thanks.
Kaveh
<graph-theory><co.combinatorics><graph-algorithms><data-sets>
Graphs to download
scatman
# Graphs to download

(Asked by: username_0 on 2011-05-17)

Possible Duplicate:
Data for testing graph algorithms 

I recently developed a parallel algorithm to solve the vertex cover problem.
now i need some graphs so i can test the speed of my algorithm vs the sequential code.
where can i find graphs? i am looking for something similar to this text file:  
3 3
1 0
1 2
0 2

the first 2 numbers (3 and 3) states that there are 3 vertices and 3 edges in the graph. following this line is 3 edges.

**Tags:** graph-theory, co.combinatorics, graph-algorithms, data-sets

> **Comments:**
> **username_1**: Hi @username_0: I'm not so sure that your question is within scope, so you may want to try other SE sites as well.  
> **username_2**: Check out the answers for the related questions http://cstheory.stackexchange.com/questions/3409/graphs-from-real-life-problems http://cstheory.stackexchange.com/questions/739/data-for-testing-graph-algorithms  
> **username_3**: Related MO question [Database of graphs](http://mathoverflow.net/questions/23748/where-on-the-internet-i-can-find-database-of-graphs)  
> **username_4**: You can also generate random graphs, using packages such as Jung or R or probably any graph library. This would give you some flexibility, as you could vary the kind of graph generated by changing the various parameters available, including the kind of graph.  
> **username_5**: (The other question specifically asks for directed graphs, but I think it would be a good idea to slightly edit the question to make it more general, and then merge the answers. Also, it might be a good idea to CW the question.)  
> **username_6**: @Jukka, I have edited the other question (and in fact was going to merge the questions) but then I thought that it might not be a good thing (there is no way to reverse a merge) since this question is asking for graphs for a specific problem. (ps: as result of my closing as duplicate and reopening the question the close votes for this question has been lost. I should have been more careful. Sorry.)  
> **username_6**: Hi username_0, please read the FAQ. Specifying the format of the input is making your question too localized IMO, so I would suggest that edit that part. Also take a look at the question linked above by Jukka to see if the answers for that question would also answer your question (in which case I can merge the questions so all of the answers are in one place). Thanks.  

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## 3 answers

### Answer by username_5 on 2011-05-17. Score: 8 | Accepted answer

If you want *challenging* instances for the vertex cover problem:

<http://www.nlsde.buaa.edu.cn/~kexu/benchmarks/graph-benchmarks.htm>


---

### Answer by username_7 on 2011-05-17. Score: 3

You can check out the graphs at [NetWiki](http://netwiki.amath.unc.edu/SharedData/SharedData). Of course, you'll have to sort out the formatting yourself.


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### Answer by username_8 on 2011-05-23. Score: 2

Here's a collection of graphs that we used for analyzing a vertex cover heuristic:
<http://www.ru.is/kennarar/eyjo/vertexcover.html>

You can download a zipfile containing all the graphs here:
<http://www.ru.is/kennarar/eyjo/vertexcover/graphs.zip>

The format is not exactly as you specified but it's close enough.


---

