Re: [Neo4j] Arnoldi iteration
Lorenzo, sorry for taking so long time - missed your CLA mail. Anyway, we got it, thanks! Now, could you raise and issue in trac.neo4j.org and attach your patch against the current graph-algo trunk so we can include it into the code? Would be great to have this coming in. Cheers, /peter neubauer COO and Sales, Neo Technology GTalk: neubauer.peter Skype peter.neubauer Phone +46 704 106975 LinkedIn http://www.linkedin.com/in/neubauer Twitter http://twitter.com/peterneubauer http://www.neo4j.org - Your high performance graph database. http://www.thoughtmade.com - Scandinavia's coolest Bring-a-Thing party. On Wed, Jun 2, 2010 at 8:04 AM, Peter Neubauer peter.neuba...@neotechnology.com wrote: Lorenzo, On Mon, May 31, 2010 at 2:33 PM, Lorenzo Livi lorenz.l...@gmail.com wrote: I'll make a try with the 0.6-snapshot version and I'll let you know. yes, please get back with feedback! Tobias and Mattias have been looking closer at some of the algos in the graph-algo package but not all are totally tested through, so your feedback is greatly appreciated. The last thing: the power method is not guaranted to converge always ... especially if the graph is directed (neo4j is always directed). Then a method like Arnoldi Iteration is necessary IMHO. I've developed the simplest centrality measure, the degree centrality and I should develop PageRank and/or HITS (not now ..). Maybe you can be interested in these algos (for now the degree centrality). Let me know. Yes, we are and could include them into the graph-algo package. You can just sign the CLA and we can get going on this, http://wiki.neo4j.org/content/About_Contributor_License_Agreement /peter ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
Re: [Neo4j] Arnoldi iteration
Lorenzo, On Mon, May 31, 2010 at 2:33 PM, Lorenzo Livi lorenz.l...@gmail.com wrote: I'll make a try with the 0.6-snapshot version and I'll let you know. yes, please get back with feedback! Tobias and Mattias have been looking closer at some of the algos in the graph-algo package but not all are totally tested through, so your feedback is greatly appreciated. The last thing: the power method is not guaranted to converge always ... especially if the graph is directed (neo4j is always directed). Then a method like Arnoldi Iteration is necessary IMHO. I've developed the simplest centrality measure, the degree centrality and I should develop PageRank and/or HITS (not now ..). Maybe you can be interested in these algos (for now the degree centrality). Let me know. Yes, we are and could include them into the graph-algo package. You can just sign the CLA and we can get going on this, http://wiki.neo4j.org/content/About_Contributor_License_Agreement /peter ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
Re: [Neo4j] Arnoldi iteration
Ciao Peter,
It's not easy to provide you a test case suitable for debugging ...
I'm running many test to complete my thesis (I'm citing neo4j) on some
natural language processing problem. My dataset is very large. Let me
think about it
If you can access the sources of 0.3 stable version, you can see these lines:
// If the first value is negative (possibly the whole vector), negate
// the whole vector
if ( values.get( nodeSet.iterator().next() ) 0 )
{
for ( Node node : nodeSet )
{
values.put( node, -values.get( node ) );
}
}
That's always true? if the first one is negative, then you should
always negate the whole vector??
I'll make a try with the 0.6-snapshot version and I'll let you know.
The last thing: the power method is not guaranted to converge always
... especially if the graph is directed (neo4j is always directed).
Then a method like Arnoldi Iteration is necessary IMHO.
I've developed the simplest centrality measure, the degree centrality
and I should develop PageRank and/or HITS (not now ..). Maybe you can
be interested in these algos (for now the degree centrality). Let me
know.
Best regards,
Lorenzo
On Sun, May 30, 2010 at 8:56 PM, Peter Neubauer
peter.neuba...@neotechnology.com wrote:
Lorenzo,
I think the lesser used algos are in need of seeing over. Could you
provide a failing testcase that can be fixed in order to get the
Eigenvector into shape? Would be great in order to get the problem
pinned down while you are at it!
Cheers,
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Re: [Neo4j] Arnoldi iteration
Lorenzo, I think the lesser used algos are in need of seeing over. Could you provide a failing testcase that can be fixed in order to get the Eigenvector into shape? Would be great in order to get the problem pinned down while you are at it! Cheers, /peter neubauer COO and Sales, Neo Technology GTalk: neubauer.peter Skype peter.neubauer Phone +46 704 106975 LinkedIn http://www.linkedin.com/in/neubauer Twitter http://twitter.com/peterneubauer http://www.neo4j.org - Your high performance graph database. http://www.thoughtmade.com - Scandinavia's coolest Bring-a-Thing party. On Fri, May 28, 2010 at 9:04 PM, Lorenzo Livi lorenz.l...@gmail.com wrote: Hi all, I'm noticing that sometimes I get negative values for the eigenvector calculated by the algorithm. This shouldn't happen ... I'm using 0.3 stable version of the package. I Should update to 0.6-SNAPSHOT ??? Best regards, Lorenzo ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
