Package org.apache.lucene.search.similarities

Class Similarity.SimWeight

  • Direct Known Subclasses:
    BasicStats
    Enclosing class:
    Similarity
    public abstract static class Similarity.SimWeight
extends java.lang.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

      All Methods Instance Methods Abstract Methods 
      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 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, 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.