Class BoostingQuery

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This code was originally made available here: [WWW] http://marc.theaimsgroup.com/?l=lucene-user&m=108058407130459&w=2 and is documented here: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

Inheritance

object

Query

BoostingQuery

Inherited Members

Query.Boost

Query.ToString()

Query.CreateWeight(IndexSearcher)

Query.ExtractTerms(ISet<Term>)

Query.Clone()

object.Equals(object, object)

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

Namespace: Lucene.Net.Queries

Assembly: Lucene.Net.Queries.dll

Syntax

public class BoostingQuery : Query

Constructors

BoostingQuery(Query, Query, float)

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This code was originally made available here: [WWW] http://marc.theaimsgroup.com/?l=lucene-user&m=108058407130459&w=2 and is documented here: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

Declaration

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

Parameters

Type	Name	Description
Query	match
Query	context
float	boost

Methods

Equals(object)

Determines whether the specified object is equal to the current object.

Declaration

public override bool Equals(object obj)

Parameters

Type	Name	Description
object	obj	The object to compare with the current object.

Returns

Type	Description
bool	true if the specified object is equal to the current object; otherwise, false.

Overrides

Query.Equals(object)

GetHashCode()

Serves as the default hash function.

Declaration

public override int GetHashCode()

Returns

Type	Description
int	A hash code for the current object.

Overrides

Lucene.Net.Search.Query.GetHashCode()

Rewrite(IndexReader)

Expert: called to re-write queries into primitive queries. For example, a Lucene.Net.Search.PrefixQuery will be rewritten into a Lucene.Net.Search.BooleanQuery that consists of Lucene.Net.Search.TermQuerys.

Declaration

public override Query Rewrite(IndexReader reader)

Parameters

Type	Name	Description
IndexReader	reader

Returns

Type	Description
Query

Overrides

Lucene.Net.Search.Query.Rewrite(Lucene.Net.Index.IndexReader)

ToString(string)

Prints a query to a string, with field assumed to be the default field and omitted.

Declaration

public override string ToString(string field)

Parameters

Type	Name	Description
string	field

Returns

Type	Description
string

Overrides

Query.ToString(string)