org.eml.sir.retr
Class AdjustableSimilarity

java.lang.Object
  org.apache.lucene.search.Similarity
      org.eml.sir.retr.AdjustableSimilarity

public class AdjustableSimilarity

extends org.apache.lucene.search.Similarity

Adjustable scoring implementation.

Field Summary

static char	IDF_F Constant for idf factor of AdjustableSimilarity.
static char	IDF_P Constant for idf factor of AdjustableSimilarity.
static char	TF_1 Constant for tf factor of AdjustableSimilarity.
static char	TF_FREQ Constant for tf factor of AdjustableSimilarity.
static char	TF_SQRT Constant for tf factor of AdjustableSimilarity.

Constructor Summary

AdjustableSimilarity()

AdjustableSimilarity(char tfAlg, char idfAlg)
Create a new AdjustableSimilarity instance.

Method Summary

float	coord(int overlap, int maxOverlap) Implemented as overlap / maxOverlap.
char	getIdfAlg() Return the idf algorithm (factor) of this AdjustableSimilarity.
char	getTfAlg() Return the tf algorithm (factor) of this AdjustableSimilarity.
float	idf(int docFreq, int numDocs) Depends on the idf algorithm (factor) setting.
float	lengthNorm(java.lang.String fieldName, int numTerms) Implemented as 1/sqrt(numTerms).
float	queryNorm(float sumOfSquaredWeights) Implemented as 1/sqrt(sumOfSquaredWeights).
void	setIdfAlg(char idfAlg) Set the idf algorithm (factor) of this AdjustableSimilarity.
void	setTfAlg(char tfAlg) Set the tf algorithm (factor) of this AdjustableSimilarity.
float	sloppyFreq(int distance) Implemented as 1 / (distance + 1).
float	tf(float freq) Depends on the tf algorithm (factor) setting.

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

decodeNorm, encodeNorm, getDefault, idf, idf, setDefault, tf

Methods inherited from class java.lang.Object

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

Field Detail

TF_1

public static final char TF_1

Constant for tf factor of AdjustableSimilarity. (tf = 1)

See Also:

Constant Field Values

TF_FREQ

public static final char TF_FREQ

Constant for tf factor of AdjustableSimilarity. (tf = frequency)

See Also:

Constant Field Values

TF_SQRT

public static final char TF_SQRT

Constant for tf factor of AdjustableSimilarity. (tf = sqrt(frequency))

See Also:

Constant Field Values

IDF_F

public static final char IDF_F

Constant for idf factor of AdjustableSimilarity. (idf = log(N/(n+1))+1)

See Also:

Constant Field Values

IDF_P

public static final char IDF_P

Constant for idf factor of AdjustableSimilarity. (idf = log((N-n)/(n+1)+1)+1)

See Also:

Constant Field Values

Constructor Detail

AdjustableSimilarity

public AdjustableSimilarity()

AdjustableSimilarity

public AdjustableSimilarity(char tfAlg,
                            char idfAlg)

Create a new AdjustableSimilarity instance.

Method Detail

getIdfAlg

public char getIdfAlg()

Return the idf algorithm (factor) of this AdjustableSimilarity.

setIdfAlg

public void setIdfAlg(char idfAlg)

Set the idf algorithm (factor) of this AdjustableSimilarity.

getTfAlg

public char getTfAlg()

Return the tf algorithm (factor) of this AdjustableSimilarity.

setTfAlg

public void setTfAlg(char tfAlg)

Set the tf algorithm (factor) of this AdjustableSimilarity.

lengthNorm

public float lengthNorm(java.lang.String fieldName,
                        int numTerms)

Implemented as 1/sqrt(numTerms).

queryNorm

public float queryNorm(float sumOfSquaredWeights)

Implemented as 1/sqrt(sumOfSquaredWeights).

tf

public float tf(float freq)

Depends on the tf algorithm (factor) setting.

sloppyFreq

public float sloppyFreq(int distance)

Implemented as 1 / (distance + 1).

idf

public float idf(int docFreq,
                 int numDocs)

Depends on the idf algorithm (factor) setting.

coord

public float coord(int overlap,
                   int maxOverlap)

Implemented as overlap / maxOverlap.