org.apache.lucene.search
Class BoostingQuery

java.lang.Object
  extended by org.apache.lucene.search.Query
      extended by org.apache.lucene.search.BoostingQuery
All Implemented Interfaces:
Serializable, Cloneable

public class BoostingQuery
extends Query

The BoostingQuery class can be used to effectively demote results that match a given query. Unlike the "NOT" clause, this still selects documents that contain undesirable terms, but reduces their overall score: Query balancedQuery = new BoostingQuery(positiveQuery, negativeQuery, 0.01f); In this scenario the positiveQuery contains the mandatory, desirable criteria which is used to select all matching documents, and the negativeQuery contains the undesirable elements which are simply used to lessen the scores. Documents that match the negativeQuery have their score multiplied by the supplied "boost" parameter, so this should be less than 1 to achieve a demoting effect This code was originally made available here: [WWW] http://marc.theaimsgroup.com/?l=lucene-user&m=108058407130459&w=2 and is documented here: http://wiki.apache.org/lucene-java/CommunityContributions

See Also:
Serialized Form

Constructor Summary
BoostingQuery(Query match, Query context, float boost)
           
 
Method Summary
 Query rewrite(IndexReader reader)
           
 String toString(String field)
           
 
Methods inherited from class org.apache.lucene.search.Query
clone, combine, createWeight, extractTerms, getBoost, getSimilarity, mergeBooleanQueries, setBoost, toString, weight
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

BoostingQuery

public BoostingQuery(Query match,
                     Query context,
                     float boost)
Method Detail

rewrite

public Query rewrite(IndexReader reader)
              throws IOException
Overrides:
rewrite in class Query
Throws:
IOException

toString

public String toString(String field)
Specified by:
toString in class Query


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