Hi, thanks for reply. Yeah, I've read the Similarity class documentation several times, but I need some tip.
My queries are BooleanQueries but they always have the same structure (the same structure of the docs, they are actually docs from collection): 3 fields. What if I simplify the similarity scores, by removing coord factor and just leaving the cosine similarity which is comparable ? I want to underline the fact that my boolean queries are just a combination of "field:term" items, and I always have the same 3 fields with different terms obviously. Thanks On 28 March 2011 10:03, Uwe Schindler <[email protected]> wrote: > No, scores are in general not comparable between different queries. The > problem lies in many things: > - Each query has a norm factor that makes it more compareable if they are > sub clauses of a BooleanQuery. But you are right, this norm factor should > be > the same. > - Some queries like FuzzyQuery rely on the terms in index and those matches > the query > - Inside Boolean queries, there is also a coord-factor involved > > If you are always using the same simple type of query (e.g. simple > TermQuery, only with different term) on the same index, you can compare the > scores. As soon as you are using complex queries (e.g several terms > compared > in a BooleanQuery as QueryParser produces), the scores are no longer > comparable. > > You can read more on all factors that are included in scoring: > > http://lucene.apache.org/java/3_0_3/api/core/org/apache/lucene/search/Simila > rity.html > > ----- > Uwe Schindler > H.-H.-Meier-Allee 63, D-28213 Bremen > http://www.thetaphi.de > eMail: [email protected] > > > > -----Original Message----- > > From: Patrick Diviacco [mailto:[email protected]] > > Sent: Monday, March 28, 2011 9:44 AM > > To: [email protected] > > Subject: comparing lucene scores across queries > > > > Hi, > > > > sorry I've already asked few days ago, but I got no reply and I really > need > > some help on this.. > > > > I'm running several queries against a doc collection. The queries are > > documents of the collection itself, I need to measure how similar is each > > document to the rest of the collection. > > > > Now, Lucene returns me a score per query, but I've been told such score > is > > not comparable across queries. Is this correct ? > > > > For example, arem't these scores comparable ? > > query1, score:8.324234 > > query2, score:3.324238 > > > > If so, why not ? Isn't the cosine similarity between the query vector and > > collection docs vectors ? I really need a comparable measure. > > > > thanks > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [email protected] > For additional commands, e-mail: [email protected] > >
