public class Bo1 extends QueryExpansionModel
averageDocumentLength, collectionLength, documentFrequency, EXPANSION_DOCUMENTS, EXPANSION_TERMS, idf, maxTermFrequency, numberOfDocuments, PARAMETER_FREE, ROCCHIO_BETA, totalDocumentLength
Constructor and Description |
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Bo1()
A default constructor.
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Modifier and Type | Method and Description |
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String |
getInfo()
Returns the name of the model.
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double |
parameterFreeNormaliser()
This method computes the normaliser of parameter-free query expansion.
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double |
parameterFreeNormaliser(double maxTermFrequency,
double collectionLength,
double totalDocumentLength)
This method computes the normaliser of parameter-free query expansion.
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double |
score(double withinDocumentFrequency,
double termFrequency)
This method implements the query expansion model.
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double |
score(double withinDocumentFrequency,
double termFrequency,
double totalDocumentLength,
double collectionLength,
double averageDocumentLength)
This method implements the query expansion model.
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initialise, setAverageDocumentLength, setCollectionLength, setDocumentFrequency, setMaxTermFrequency, setNumberOfDocuments, setTotalDocumentLength
public final 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.Terrier 4.0. Copyright © 2004-2014 University of Glasgow