Package org.apache.lucene.search.similarities

# Class AxiomaticF2LOG

java.lang.Object
org.apache.lucene.search.similarities.Similarity
org.apache.lucene.search.similarities.SimilarityBase
org.apache.lucene.search.similarities.Axiomatic
org.apache.lucene.search.similarities.AxiomaticF2LOG

public class AxiomaticF2LOG extends Axiomatic
F2EXP is defined as Sum(tfln(term_doc_freq, docLen)*IDF(term)) where IDF(t) = ln((N+1)/df(t)) N=total num of docs, df=doc freq

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

- ## Nested Class Summary

  ## Nested classes/interfaces inherited from class org.apache.lucene.search.similarities.Similarity

  `Similarity.BulkSimScorer, Similarity.SimScorer`

- ## Field Summary

  ### Fields inherited from class org.apache.lucene.search.similarities.Axiomatic

  `k, queryLen, s`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `AxiomaticF2LOG()`
  Default constructor
  `AxiomaticF2LOG(float s)`
  Constructor setting s only, letting k and queryLen to default

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected double`
  `gamma(BasicStats stats, double freq, double docLen)`
  compute the gamma component
  `protected double`
  `idf(BasicStats stats, double freq, double docLen)`
  compute the inverted document frequency component
  `protected Explanation`
  `idfExplain(BasicStats stats, double freq, double docLen)`
  Explain the score of the inverted document frequency component for a single document
  `protected double`
  `ln(BasicStats stats, double freq, double docLen)`
  compute the document length component
  `protected Explanation`
  `lnExplain(BasicStats stats, double freq, double docLen)`
  Explain the score of the document length component for a single document
  `protected double`
  `tf(BasicStats stats, double freq, double docLen)`
  compute the term frequency component
  `protected Explanation`
  `tfExplain(BasicStats stats, double freq, double docLen)`
  Explain the score of the term frequency component for a single document
  `protected double`
  `tfln(BasicStats stats, double freq, double docLen)`
  compute the mixed term frequency and document length component
  `protected Explanation`
  `tflnExplain(BasicStats stats, double freq, double docLen)`
  Explain the score of the mixed term frequency and document length component for a single document
  `String`
  `toString()`
  Name of the axiomatic method.

  ### Methods inherited from class org.apache.lucene.search.similarities.Axiomatic

  `explain, explain, score`

  ### Methods inherited from class org.apache.lucene.search.similarities.SimilarityBase

  `fillBasicStats, log2, newStats, scorer`

  ### Methods inherited from class org.apache.lucene.search.similarities.Similarity

  `computeNorm, getDiscountOverlaps`

  ### Methods inherited from class java.lang.Object

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

- ## Constructor Details

  - ### AxiomaticF2LOG

    public AxiomaticF2LOG(float s)
    Constructor setting s only, letting k and queryLen to default
    Parameters:
      `s` - hyperparam for the growth function

  - ### AxiomaticF2LOG

    public AxiomaticF2LOG()
    Default constructor

- ## Method Details

  - ### toString

    public String toString()
    Description copied from class: `Axiomatic`
    Name of the axiomatic method.
    Specified by:
      `toString` in class `Axiomatic`

  - ### tf

    protected double tf(BasicStats stats, double freq, double docLen)
    compute the term frequency component
    Specified by:
      `tf` in class `Axiomatic`

  - ### ln

    protected double ln(BasicStats stats, double freq, double docLen)
    compute the document length component
    Specified by:
      `ln` in class `Axiomatic`

  - ### tfln

    protected double tfln(BasicStats stats, double freq, double docLen)
    compute the mixed term frequency and document length component
    Specified by:
      `tfln` in class `Axiomatic`

  - ### idf

    protected double idf(BasicStats stats, double freq, double docLen)
    compute the inverted document frequency component
    Specified by:
      `idf` in class `Axiomatic`

  - ### gamma

    protected double gamma(BasicStats stats, double freq, double docLen)
    compute the gamma component
    Specified by:
      `gamma` in class `Axiomatic`

  - ### tfExplain

    protected Explanation tfExplain(BasicStats stats, double freq, double docLen)
    Description copied from class: `Axiomatic`
    Explain the score of the term frequency component for a single document
    Specified by:
      `tfExplain` in class `Axiomatic`
    Parameters:
      `stats` - the corpus level statistics
      `freq` - number of occurrences of term in the document
      `docLen` - the document length
    Returns:
      Explanation of how the tf component was computed

  - ### lnExplain

    protected Explanation lnExplain(BasicStats stats, double freq, double docLen)
    Description copied from class: `Axiomatic`
    Explain the score of the document length component for a single document
    Specified by:
      `lnExplain` in class `Axiomatic`
    Parameters:
      `stats` - the corpus level statistics
      `freq` - number of occurrences of term in the document
      `docLen` - the document length
    Returns:
      Explanation of how the ln component was computed

  - ### tflnExplain

    protected Explanation tflnExplain(BasicStats stats, double freq, double docLen)
    Description copied from class: `Axiomatic`
    Explain the score of the mixed term frequency and document length component for a single document
    Specified by:
      `tflnExplain` in class `Axiomatic`
    Parameters:
      `stats` - the corpus level statistics
      `freq` - number of occurrences of term in the document
      `docLen` - the document length
    Returns:
      Explanation of how the tfln component was computed

  - ### idfExplain

    protected Explanation idfExplain(BasicStats stats, double freq, double docLen)
    Description copied from class: `Axiomatic`
    Explain the score of the inverted document frequency component for a single document
    Specified by:
      `idfExplain` in class `Axiomatic`
    Parameters:
      `stats` - the corpus level statistics
      `freq` - number of occurrences of term in the document
      `docLen` - the document length
    Returns:
      Explanation of how the idf component was computed