ivory.ffg.score

Class BM25ScoringFunction

java.lang.Object

ivory.ffg.score.BM25ScoringFunction

All Implemented Interfaces:

ScoringFunction

public class BM25ScoringFunction
extends Object
implements ScoringFunction

Implementation of the BM25 scoring function.

Author:

Nima Asadi

Constructor Summary

Constructors

Constructor and Description
BM25ScoringFunction(float k1, float b)

Method Summary

Methods

Modifier and Type	Method and Description
float	computePhraseScore(int dl, int tf, GlobalStats stat) Computes phrase feature value.
float	computeTermScore(int term, int dl, int tf, GlobalStats stat) Computes term feature value.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

BM25ScoringFunction

public BM25ScoringFunction(float k1,
                   float b)

Parameters:

k1 - BM25 parameter k1

b - BM25 parameter b

Method Detail

computePhraseScore

public float computePhraseScore(int dl,
                       int tf,
                       GlobalStats stat)

Description copied from interface: ScoringFunction

Computes phrase feature value.

Specified by:

computePhraseScore in interface ScoringFunction

Parameters:

dl - Document length

tf - Phrase frequency

stat - Global statistics

Returns:

Feature value

computeTermScore

public float computeTermScore(int term,
                     int dl,
                     int tf,
                     GlobalStats stat)

Description copied from interface: ScoringFunction

Computes term feature value.

Specified by:

computeTermScore in interface ScoringFunction

dl - Document length

tf - Term frequency

stat - Global statistics

Returns:

Feature value

toString

public String toString()

Overrides:

toString in class Object