org.apache.lucene.search.similarities

Class BasicStats

java.lang.Object

org.apache.lucene.search.similarities.Similarity.SimWeight

org.apache.lucene.search.similarities.BasicStats

Direct Known Subclasses:

LMSimilarity.LMStats

public class BasicStats
extends Similarity.SimWeight

Stores all statistics commonly used ranking methods.

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

Field Summary

Fields

Modifier and Type	Field and Description
protected float	avgFieldLength The average field length.
protected long	docFreq The document frequency.
protected long	numberOfDocuments The number of documents.
protected long	numberOfFieldTokens The total number of tokens in the field.
protected float	queryBoost Query's inner boost.
protected float	topLevelBoost Any outer query's boost.
protected float	totalBoost For most Similarities, the immediate and the top level query boosts are not handled differently.
protected long	totalTermFreq The total number of occurrences of this term across all documents.

Constructor Summary

Constructors

Constructor and Description
BasicStats(String field, float queryBoost) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
float	getAvgFieldLength() Returns the average field length.
long	getDocFreq() Returns the document frequency.
long	getNumberOfDocuments() Returns the number of documents.
long	getNumberOfFieldTokens() Returns the total number of tokens in the field.
float	getTotalBoost() Returns the total boost.
long	getTotalTermFreq() Returns the total number of occurrences of this term across all documents.
float	getValueForNormalization() The square of the raw normalization value.
void	normalize(float queryNorm, float topLevelBoost) No normalization is done.
protected float	rawNormalizationValue() Computes the raw normalization value.
void	setAvgFieldLength(float avgFieldLength) Sets the average field length.
void	setDocFreq(long docFreq) Sets the document frequency.
void	setNumberOfDocuments(long numberOfDocuments) Sets the number of documents.
void	setNumberOfFieldTokens(long numberOfFieldTokens) Sets the total number of tokens in the field.
void	setTotalTermFreq(long totalTermFreq) Sets the total number of occurrences of this term across all documents.

Methods inherited from class java.lang.Object

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

Field Detail

numberOfDocuments

protected long numberOfDocuments

The number of documents.

numberOfFieldTokens

protected long numberOfFieldTokens

The total number of tokens in the field.

avgFieldLength

protected float avgFieldLength

The average field length.

docFreq

protected long docFreq

The document frequency.

totalTermFreq

protected long totalTermFreq

The total number of occurrences of this term across all documents.

queryBoost

protected final float queryBoost

Query's inner boost.

topLevelBoost

protected float topLevelBoost

Any outer query's boost.

totalBoost

protected float totalBoost

For most Similarities, the immediate and the top level query boosts are not handled differently. Hence, this field is just the product of the other two.

Constructor Detail

BasicStats

public BasicStats(String field,
          float queryBoost)

Constructor. Sets the query boost.

Method Detail

getNumberOfDocuments

public long getNumberOfDocuments()

Returns the number of documents.

setNumberOfDocuments

public void setNumberOfDocuments(long numberOfDocuments)

Sets the number of documents.

getNumberOfFieldTokens

public long getNumberOfFieldTokens()

Returns the total number of tokens in the field.

See Also:

Terms.getSumTotalTermFreq()

setNumberOfFieldTokens

public void setNumberOfFieldTokens(long numberOfFieldTokens)

Sets the total number of tokens in the field.

See Also:

Terms.getSumTotalTermFreq()

getAvgFieldLength

public float getAvgFieldLength()

Returns the average field length.

setAvgFieldLength

public void setAvgFieldLength(float avgFieldLength)

Sets the average field length.

getDocFreq

public long getDocFreq()

Returns the document frequency.

setDocFreq

public void setDocFreq(long docFreq)

Sets the document frequency.

getTotalTermFreq

public long getTotalTermFreq()

Returns the total number of occurrences of this term across all documents.

setTotalTermFreq

public void setTotalTermFreq(long totalTermFreq)

Sets the total number of occurrences of this term across all documents.

getValueForNormalization

public float getValueForNormalization()

The square of the raw normalization value.

Specified by:

getValueForNormalization in class Similarity.SimWeight

See Also:

rawNormalizationValue()

rawNormalizationValue

protected float rawNormalizationValue()

Computes the raw normalization value. This basic implementation returns the query boost. Subclasses may override this method to include other factors (such as idf), or to save the value for inclusion in normalize(float, float), etc.

normalize

public void normalize(float queryNorm,
             float topLevelBoost)

No normalization is done. topLevelBoost is saved in the object, however.

Specified by:

normalize in class Similarity.SimWeight

getTotalBoost

public float getTotalBoost()

Returns the total boost.