Package 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
    Description
    SimWeight()
    Sole constructor.

  • Method Summary

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

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • SimWeight

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

  • Method Details

    • 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, its 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 topLevelBoost)
      Assigns the query normalization factor and boost from parent queries to this.

      NOTE: a Similarity implementation might not use this normalized value at all, its not required. However, its usually a good idea to at least incorporate the topLevelBoost (e.g. from an outer BooleanQuery) into its score.