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TextQueryRetMethod Class Reference

#include <TextQueryRetMethod.hpp>

Inheritance diagram for TextQueryRetMethod:

List of all members.

Public Methods
	TextQueryRetMethod (Index &ind,ScoreAccumulator &accumulator)
virtual	~TextQueryRetMethod ()
virtual TextQueryRep*	computeTextQueryRep (TextQuery &qry)=0
	compute the query representation for a text query (caller responsible for deleting the memory of the generated new instance).
virtual QueryRep*	computeQueryRep (Query &qry)
	overriding abstract class method.
virtual double	scoreDoc (QueryRep &qry,int docID)
	ooverriding abstract class method.
virtual void	scoreCollection (QueryRep &qry,IndexedRealVector &results)
	ooverriding abstract class method with a general efficient inverted index scoring procedure.
virtual DocumentRep*	computeDocRep (int docID)=0
	compute the doc representation (caller responsible for deleting the memory of the generated new instance).
virtual ScoreFunction*	scoreFunc ()=0
	return the scoring function pointer.
virtual void	updateQuery (QueryRep &qryRep,DocIDSet &relDocs)
	update the query.
virtual void	updateTextQuery (TextQueryRep &qryRep,DocIDSet &relDocs)=0
	Modify/update the query representation based on a set (presumably) relevant documents.
virtual void	scoreInvertedIndex (QueryRep &qryRep,IndexedRealVector &scores,bool scoreAll=false)
	Efficient scoring with the inverted index. More...
virtual double	scoreDocVector (TextQueryRep &qry,int docID,FreqVector &docVector)
Protected Attributes
ScoreAccumulator&	scAcc

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Detailed Description

A text query retrieval method is determined by specifying the following elements

• A method to compute the query representation
• A method to compute the doc representation
• The scoring function
• A method to update the query representation based on a set of (relevant) documents

Given a query q =(q1,q2,...,qN) and a document d=(d1,d2,...,dN), where q1,...,qN and d1,...,dN are terms, TextQueryRetMethod assumes the following general scoring function:

<blockquote>

s(q,d) = g(w(q1,d1,q,d) + ... + w(qN,dN,q,d),q,d)

</blockquote> That is, the score of a document d against a query q is a function g of the accumulated weight w for each matched term.

The score is thus determined by two functions g and w; both may depend on the whole query or document. The function w gives the weight of each matched term, while the function g makes it possible to perform any further transformation of the sum of the weight of all matched terms based on the "summary" information of a query or a document (e.g., document length).

TextQueryRep, DocumentRep, and ScoreFunction are designed to support this general scoring function in the following way:

A ScoreFunction is responsible for defining the two functions g and w. A TextQueryRep provides any information required for scoring from the query side (e.g., query term frequency). Similarly, a DocumentRep provides any information required for scoring from the document side. Furthermore, a TextQueryRep supports iteration over all query terms, allowing easy accumulation of weights over matched terms. The weighting function w and score adjustment function g typically assume and depend on some particular information and representation of the query and document, so a specific ScoreFunction (for a specific retrieval method) only works for some specific TextQueryRep and DocumentRep that are appropriate for the specific retrieval method.

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Constructor & Destructor Documentation

TextQueryRetMethod::TextQueryRetMethod ( Index & ind, ScoreAccumulator & accumulator ) [inline]

TextQueryRetMethod::~TextQueryRetMethod ( ) [inline, virtual]

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Member Function Documentation

DocumentRep * TextQueryRetMethod::computeDocRep ( int docID ) [pure virtual]

compute the doc representation (caller responsible for deleting the memory of the generated new instance). Reimplemented in OkapiRetMethod, SimpleKLRetMethod, and TFIDFRetMethod.

QueryRep * TextQueryRetMethod::computeQueryRep ( Query & qry ) [inline, virtual]

overriding abstract class method. Reimplemented from RetrievalMethod.

TextQueryRep * TextQueryRetMethod::computeTextQueryRep ( TextQuery & qry ) [pure virtual]

compute the query representation for a text query (caller responsible for deleting the memory of the generated new instance). Reimplemented in OkapiRetMethod, SimpleKLRetMethod, and TFIDFRetMethod.

void TextQueryRetMethod::scoreCollection ( QueryRep & qry, IndexedRealVector & results ) [virtual]

ooverriding abstract class method with a general efficient inverted index scoring procedure. Reimplemented from RetrievalMethod.

double TextQueryRetMethod::scoreDoc ( QueryRep & qry, int docID ) [virtual]

ooverriding abstract class method. Reimplemented from RetrievalMethod.

double TextQueryRetMethod::scoreDocVector ( TextQueryRep & qRep, int docID, FreqVector & docVector ) [virtual]

ScoreFunction * TextQueryRetMethod::scoreFunc ( ) [pure virtual]

return the scoring function pointer. Reimplemented in OkapiRetMethod, SimpleKLRetMethod, and TFIDFRetMethod.

void TextQueryRetMethod::scoreInvertedIndex ( QueryRep & qRep, IndexedRealVector & scores, bool scoreAll = false ) [virtual]

Efficient scoring with the inverted index. a general scoring procedure shared by many different models (assuming "sortedScores has memory allocated)

void TextQueryRetMethod::updateQuery ( QueryRep & qryRep, DocIDSet & relDocs ) [inline, virtual]

update the query. Reimplemented from RetrievalMethod.

void TextQueryRetMethod::updateTextQuery ( TextQueryRep & qryRep, DocIDSet & relDocs ) [pure virtual]

Modify/update the query representation based on a set (presumably) relevant documents. Reimplemented in OkapiRetMethod, SimpleKLRetMethod, and TFIDFRetMethod.

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Member Data Documentation

ScoreAccumulator & TextQueryRetMethod::scAcc [protected]

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The documentation for this class was generated from the following files:

• TextQueryRetMethod.hpp
• TextQueryRetMethod.cpp

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