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From "Claudia Grieco" <gri...@crmpa.unisa.it>
Subject R: Using Item Based recommenders as content based recommenders
Date Fri, 24 Jul 2009 07:22:03 GMT
Thanks.
Do you know of any fast way to obtain document-document similarity in Lucene and write it
to a text Mahout can read?

Ah, while playing a bit with item based recommenders I found a bug in MySQLJDBCDataModel
// getNumPreferenceForItemsSQL
"SELECT COUNT(1) FROM " + preferenceTable + " tp1 INNER JOIN " + preferenceColumn + " tp2
" +
          "ON (tp1." + userIDColumn + "=tp2." + userIDColumn + ") " +
          "WHERE tp1." + itemIDColumn + "=? and tp2." + itemIDColumn + "=?");
  

It should be
"SELECT COUNT(1) FROM " + preferenceTable + " tp1 INNER JOIN " + preferenceTable....


-----Messaggio originale-----
Da: Sean Owen [mailto:srowen@gmail.com] 
Inviato: giovedì 23 luglio 2009 20.51
A: mahout-user@lucene.apache.org
Oggetto: Re: Using Item Based recommenders as content based recommenders

Yes, this is entirely reasonable.

You could also proceed by pre-computing user-user similarities and
using a user-based recommender. While it seems very much the same, I
wouldn't do that actually. Pre-computing kind of relies on the
assumption that similarities won't change much as you learn more, and
that is far more true of docs than users.




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