Hi, Once you have executed the query the TopDocs collector gives you the maximum score. Then you just need to normalize on your own.
But keep in mind: This is not always a good idea, because the maximum score and the score of the first document does not mean to be useful to compare. E.g. if the first, top-ranking result is a very bad match and no better ones are there, there is not reason to say it's a 100% hit! BTW: Lucene up to version 6 had some internal normalization in place, but this was removed in Lucene 7. The reason is simple: The scores are calculated just to compare them inside the same result set. They were never implemented to be used across different indexes or queries. ----- Uwe Schindler Achterdiek 19, D-28357 Bremen http://www.thetaphi.de eMail: u...@thetaphi.de > -----Original Message----- > From: Rifat [mailto:rifatozcan1...@gmail.com] > Sent: Tuesday, June 27, 2017 11:46 AM > To: java-user@lucene.apache.org > Subject: Is it possible to normalise BM25 scores in the query level? > > Hi all, > > I searched for this a lot but could not find a clear answer, yet. is there a > way such that Lucene (or Elasticsearch) provides query level normalization > of BM25 scores. Because BM25 scores varies considerably across queries. For > example, is it possible to get scores normalised by the max score for that > query? Since lucene processes docs one at a time and return score for that > document, at that moment, it seems not easy to do the normalisation. > > thanks, > rifat > > > > > -- > View this message in context: http://lucene.472066.n3.nabble.com/Is-it- > possible-to-normalise-BM25-scores-in-the-query-level-tp4342991.html > Sent from the Lucene - Java Users mailing list archive at Nabble.com. > > --------------------------------------------------------------------- > 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
