org.apache.lucene.search.similarities
Class BasicStats

java.lang.Object
  extended by org.apache.lucene.search.similarities.Similarity.SimWeight
      extended by 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
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
BasicStats(String field, float queryBoost)
          Constructor.
 
Method Summary
 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.



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