Of course IDF is a factor too meaning a match on a single rare (to the overall index) term may be worth more than a match on 2 different common (to the index) terms. As Ian suggests a custom Similarity implementation can be used to tune this out.
----- Original Message ---- From: Ian Lea <ian....@gmail.com> To: java-user@lucene.apache.org Sent: Thu, 19 May, 2011 14:36:56 Subject: Re: Ranking docs with all terms higher A little test shows that Mike is correct and lucene does already do this. With norms (default) nacho foo bar, score=0.8660254 foo bar bar, score=0.46461558 nacho nacho nacho nacho, score=0.19245009 Without norms nacho foo bar, score=1.7320508 foo bar bar, score=0.92923117 nacho nacho nacho nacho, score=0.38490018 Lucene 3.1.0, nothing else in the index. If you need to, you can tweak the scoring by providing a custom implementation of oal.search.Similarity. -- Ian. On Thu, May 19, 2011 at 1:34 PM, Michael McCandless <luc...@mikemccandless.com> wrote: > I believe Lucene already does this, with the 'coord' factor in > BooleanQuery, which is on by default (ie, if you just "new > BooleanQuery()"). > > Ie your doc c will get a coord factor of 1.0, doc b gets 0.666..., doc > a gets 0.3333. > > That said, if the term freq is high enough (ie doc a has nacho 4 > times), that may give it a high enough score to overcome its coord > disadvantage (I'm not sure). > > Mike > > http://blog.mikemccandless.com > > On Wed, May 18, 2011 at 10:14 PM, Christopher Condit <con...@sdsc.edu> wrote: >> Let's say I have the query >> (nacho OR foo OR bar) >> >> and some documents (single field with norms off) >> doc a: nacho nacho nacho nacho >> doc b: foo bar bar >> doc c: nacho foo bar >> >> I'm interested in all of these documents but I would like c to score the >> highest since it contains all of the search terms, b to score second >> because it has two, and a to score the third because it has one. What's >> the best way to get Lucene to do this? >> >> Thanks, >> -Chris >> >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org >> For additional commands, e-mail: java-user-h...@lucene.apache.org >> >> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-user-h...@lucene.apache.org > > --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
