Class MultiSimilarity

Implements the CombSUM method for combining evidence from multiple similarity values described in: Joseph A. Shaw, Edward A. Fox. In Text REtrieval Conference (1993), pp. 243-252

Note

This API is experimental and might change in incompatible ways in the next release.

Inheritance

object

Similarity

MultiSimilarity

Inherited Members

Similarity.Coord(int, int)

Similarity.QueryNorm(float)

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Lucene.Net.Search.Similarities

Assembly: Lucene.Net.dll

Syntax

public class MultiSimilarity : Similarity

Constructors

MultiSimilarity(Similarity[])

Creates a MultiSimilarity which will sum the scores of the provided sims.

Declaration

public MultiSimilarity(Similarity[] sims)

Parameters

Type	Name	Description
Similarity[]	sims

Fields

m_sims

the sub-similarities used to create the combined score

Declaration

protected readonly Similarity[] m_sims

Field Value

Type	Description
Similarity[]

Methods

ComputeNorm(FieldInvertState)

Computes the normalization value for a field, given the accumulated state of term processing for this field (see FieldInvertState).

Matches in longer fields are less precise, so implementations of this method usually set smaller values when state.Length is large, and larger values when

state.Length

is small.

Note

This API is experimental and might change in incompatible ways in the next release.

Declaration

public override long ComputeNorm(FieldInvertState state)

Parameters

Type	Name	Description
FieldInvertState	state	current processing state for this field

Returns

Type	Description
long	computed norm value

Overrides

ComputeWeight(float, CollectionStatistics, params TermStatistics[])

Compute any collection-level weight (e.g. IDF, average document length, etc) needed for scoring a query.

Declaration

public override Similarity.SimWeight ComputeWeight(float queryBoost, CollectionStatistics collectionStats, params TermStatistics[] termStats)

Parameters

Type	Name	Description
float	queryBoost	the query-time boost.
CollectionStatistics	collectionStats	collection-level statistics, such as the number of tokens in the collection.
TermStatistics[]	termStats	term-level statistics, such as the document frequency of a term across the collection.

Returns

Type	Description
Similarity.SimWeight	Similarity.SimWeight object with the information this Similarity needs to score a query.

Overrides

GetSimScorer(SimWeight, AtomicReaderContext)

Creates a new Similarity.SimScorer to score matching documents from a segment of the inverted index.

Declaration

public override Similarity.SimScorer GetSimScorer(Similarity.SimWeight stats, AtomicReaderContext context)

Parameters

Type	Name	Description
Similarity.SimWeight	stats
AtomicReaderContext	context	segment of the inverted index to be scored.

Returns

Type	Description
Similarity.SimScorer	Sloppy Similarity.SimScorer for scoring documents across `context`

Overrides

Exceptions

Type	Condition
IOException	if there is a low-level I/O error