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 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.