org.apache.lucene.search.similarities

Class Similarity.SimWeight

java.lang.Object

org.apache.lucene.search.similarities.Similarity.SimWeight

Direct Known Subclasses:

BasicStats

Enclosing class:

Similarity

public abstract static class Similarity.SimWeight
extends Object

Stores the weight for a query across the indexed collection. This abstract implementation is empty; descendants of Similarity should subclass SimWeight and define the statistics they require in the subclass. Examples include idf, average field length, etc.

Constructor Summary

Constructors

Constructor and Description
SimWeight() Sole constructor.

Method Summary

Modifier and Type	Method and Description
abstract float	getValueForNormalization() The value for normalization of contained query clauses (e.g.
abstract void	normalize(float queryNorm, float boost) Assigns the query normalization factor and boost from parent queries to this.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SimWeight

public SimWeight()

Sole constructor. (For invocation by subclass constructors, typically implicit.)

Method Detail

getValueForNormalization

public abstract float getValueForNormalization()

The value for normalization of contained query clauses (e.g. sum of squared weights).

NOTE: a Similarity implementation might not use any query normalization at all, it's not required. However, if it wants to participate in query normalization, it can return a value here.

normalize

public abstract void normalize(float queryNorm,
                               float boost)

Assigns the query normalization factor and boost from parent queries to this.

NOTE: a Similarity implementation might not use this normalized value at all, it's not required. However, it's usually a good idea to at least incorporate the boost into its score.

NOTE: If this method is called several times, it behaves as if only the last call was performed.