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java.lang.Object org.terrier.matching.models.queryexpansion.QueryExpansionModel org.terrier.matching.models.queryexpansion.KL
public class KL
This class implements the Kullback-Leibler divergence for query expansion. See G. Amati's PhD Thesis.
Field Summary |
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Fields inherited from class org.terrier.matching.models.queryexpansion.QueryExpansionModel |
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averageDocumentLength, collectionLength, documentFrequency, EXPANSION_DOCUMENTS, EXPANSION_TERMS, idf, maxTermFrequency, numberOfDocuments, PARAMETER_FREE, ROCCHIO_BETA, totalDocumentLength |
Constructor Summary | |
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KL()
A default constructor. |
Method Summary | |
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java.lang.String |
getInfo()
Returns the name of the model. |
double |
parameterFreeNormaliser()
This method computes the normaliser of parameter-free query expansion. |
double |
parameterFreeNormaliser(double maxTermFrequency,
double collectionLength,
double totalDocumentLength)
This method computes the normaliser of parameter-free query expansion. |
double |
score(double withinDocumentFrequency,
double termFrequency)
This method implements the query expansion model. |
double |
score(double withinDocumentFrequency,
double termFrequency,
double totalDocumentLength,
double collectionLength,
double averageDocumentLength)
This method implements the query expansion model. |
Methods inherited from class org.terrier.matching.models.queryexpansion.QueryExpansionModel |
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initialise, setAverageDocumentLength, setCollectionLength, setDocumentFrequency, setMaxTermFrequency, setNumberOfDocuments, setTotalDocumentLength |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public KL()
Method Detail |
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public final java.lang.String getInfo()
getInfo
in class QueryExpansionModel
public final double parameterFreeNormaliser()
parameterFreeNormaliser
in class QueryExpansionModel
public final double parameterFreeNormaliser(double maxTermFrequency, double collectionLength, double totalDocumentLength)
parameterFreeNormaliser
in class QueryExpansionModel
maxTermFrequency
- The maximum of the term frequency of the query terms.collectionLength
- The number of tokens in the collections.totalDocumentLength
- The sum of the length of the top-ranked documents.
public final double score(double withinDocumentFrequency, double termFrequency)
score
in class QueryExpansionModel
withinDocumentFrequency
- double The term frequency in the X top-retrieved documents.termFrequency
- double The term frequency in the collection.
public final double score(double withinDocumentFrequency, double termFrequency, double totalDocumentLength, double collectionLength, double averageDocumentLength)
score
in class QueryExpansionModel
withinDocumentFrequency
- double The term frequency in the X top-retrieved documents.termFrequency
- double The term frequency in the collection.totalDocumentLength
- double The sum of length of the X top-retrieved documents.collectionLength
- double The number of tokens in the whole collection.averageDocumentLength
- double The average document length in the collection.
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