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lemur::retrieval::XLingRetMethod Class Reference

Cross lingual retrieval method. More...

#include <XLingRetMethod.hpp>

Inheritance diagram for lemur::retrieval::XLingRetMethod:

lemur::api::RetrievalMethod List of all members.

Public Member Functions

 XLingRetMethod (const lemur::api::Index &dbIndex, const lemur::api::Index &background, lemur::dictionary::PDict &dict, lemur::api::ScoreAccumulator &accumulator, double l, double b, bool cacheDR, string &sBM, string &tBM, const lemur::api::Stopper *stp=NULL, lemur::api::Stemmer *stm=NULL)

virtual ~XLingRetMethod ()
 clean up.

virtual lemur::api::DocumentRepcomputeDocRep (lemur::api::DOCID_T docID)
 Create a document representation.

virtual double matchedTermWeight (lemur::api::TERMID_T id, double weight, const lemur::api::DocInfo *info, const lemur::api::DocumentRep *dRep) const
 Score a given term for a given document.

virtual double adjustedScore (double origScore, double pge) const
 Adjust the score for a given document.

virtual void scoreCollection (const lemur::api::QueryRep &qry, lemur::api::IndexedRealVector &results)
virtual void scoreInvertedIndex (const lemur::api::QueryRep &qryRep, lemur::api::IndexedRealVector &scores, bool scoreAll=false)
virtual lemur::api::QueryRepcomputeQueryRep (const lemur::api::Query &qry)
virtual lemur::api::QueryRepcomputeTargetKLRep (const lemur::api::QueryRep *qry)
virtual double scoreDoc (const lemur::api::QueryRep &qry, lemur::api::DOCID_T docID)
 Score a document identified by the id w.r.t. a query rep.

virtual void updateQuery (lemur::api::QueryRep &qryRep, const lemur::api::DocIDSet &relDocs)
 update the query -- noop

Protected Member Functions

virtual double scoreDocVector (const XLingQueryModel &qRep, lemur::api::DOCID_T docID, lemur::utility::FreqVector &docVector)

Protected Attributes

double lambda
double beta
double numSource
double numTarget
bool docBasedSourceSmooth
bool docBasedTargetSmooth
const lemur::api::Stopperstopper
const lemur::api::Indexsource
lemur::api::DocumentRep ** docReps
 cache document reps.

bool cacheDocReps
 whether or not to cache document representations

int docRepsSize
 number of documents plus 1, the size of the docReps array.


Detailed Description

Cross lingual retrieval method.

Translation dictionary based retrieval, scoring queries in the source language against documents in the target language using:
P(Q_s|D_t) = Prod_w_in_Q_s(lambda(Sum_t_in_D_t P(t|D_t)P(w|t) + (1-lambda)P(w|G_s)
where G_s is the background model for the source language.

Constructor & Destructor Documentation

lemur::retrieval::XLingRetMethod::XLingRetMethod const lemur::api::Index dbIndex,
const lemur::api::Index background,
lemur::dictionary::PDict dict,
lemur::api::ScoreAccumulator accumulator,
double  l,
double  b,
bool  cacheDR,
string &  sBM,
string &  tBM,
const lemur::api::Stopper stp = NULL,
lemur::api::Stemmer stm = NULL


dbIndex index for target language documents
background index for source language background model
dict PDict containing source->target translation probabilities
accumulator ScoreAccumulator for intermediate results
l lambda value to use for smoothing background model
b beta value to use for smoothing P(t|D)
cacheDR whether or not to cache document reps
sBM whether to use term frequency (tf/|V|) or term doc frequency (docCount(t)/Sum_w_in_V(docCount(w))) for the source language background model. Default is term frequency.
tBM whether to use term frequency (tf/|V|) or term doc frequency (docCount(t)/Sum_w_in_V(docCount(w))) for the targetlanguage background model. Default is term frequency.
stp source language Stopper to use when getting translations.
stm source language Stemmer to use when getting translations.

lemur::retrieval::XLingRetMethod::~XLingRetMethod  )  [virtual]

clean up.

Member Function Documentation

virtual double lemur::retrieval::XLingRetMethod::adjustedScore double  origScore,
double  pge
const [inline, virtual]

Adjust the score for a given document.

origScore the original score
pge the background probability to adjust by.
log((lambda * origScore) + ((1 - lambda) * pge))

lemur::api::DocumentRep * lemur::retrieval::XLingRetMethod::computeDocRep lemur::api::DOCID_T  docID  )  [virtual]

Create a document representation.

docID the internal document id to create the representation for
An instance of XLingDocRep

virtual lemur::api::QueryRep* lemur::retrieval::XLingRetMethod::computeQueryRep const lemur::api::Query qry  )  [inline, virtual]

virtual lemur::api::QueryRep* lemur::retrieval::XLingRetMethod::computeTargetKLRep const lemur::api::QueryRep qry  )  [virtual]

virtual double lemur::retrieval::XLingRetMethod::matchedTermWeight lemur::api::TERMID_T  id,
double  weight,
const lemur::api::DocInfo info,
const lemur::api::DocumentRep dRep
const [inline, virtual]

Score a given term for a given document.

id the term id
weight the weight for this term
info the DocInfo for this document
dRep the DocumentRep for this document
P(t|D) * P(s|t)

virtual void lemur::retrieval::XLingRetMethod::scoreCollection const lemur::api::QueryRep qry,
lemur::api::IndexedRealVector results
[inline, virtual]

virtual double lemur::retrieval::XLingRetMethod::scoreDoc const lemur::api::QueryRep qry,
lemur::api::DOCID_T  docID

Score a document identified by the id w.r.t. a query rep.

double lemur::retrieval::XLingRetMethod::scoreDocVector const XLingQueryModel qRep,
lemur::api::DOCID_T  docID,
lemur::utility::FreqVector docVector
[protected, virtual]

virtual void lemur::retrieval::XLingRetMethod::scoreInvertedIndex const lemur::api::QueryRep qryRep,
lemur::api::IndexedRealVector scores,
bool  scoreAll = false

virtual void lemur::retrieval::XLingRetMethod::updateQuery lemur::api::QueryRep qryRep,
const lemur::api::DocIDSet relDocs
[inline, virtual]

update the query -- noop

Member Data Documentation

double lemur::retrieval::XLingRetMethod::beta [protected]

bool lemur::retrieval::XLingRetMethod::cacheDocReps [protected]

whether or not to cache document representations

lemur::dictionary::PDict& lemur::retrieval::XLingRetMethod::dictionary [protected]

bool lemur::retrieval::XLingRetMethod::docBasedSourceSmooth [protected]

bool lemur::retrieval::XLingRetMethod::docBasedTargetSmooth [protected]

lemur::api::DocumentRep** lemur::retrieval::XLingRetMethod::docReps [protected]

cache document reps.

int lemur::retrieval::XLingRetMethod::docRepsSize [protected]

number of documents plus 1, the size of the docReps array.

double lemur::retrieval::XLingRetMethod::lambda [protected]

double lemur::retrieval::XLingRetMethod::numSource [protected]

double lemur::retrieval::XLingRetMethod::numTarget [protected]

lemur::api::ScoreAccumulator& lemur::retrieval::XLingRetMethod::scAcc [protected]

const lemur::api::Index& lemur::retrieval::XLingRetMethod::source [protected]

lemur::api::Stemmer* lemur::retrieval::XLingRetMethod::stemmer [protected]

const lemur::api::Stopper* lemur::retrieval::XLingRetMethod::stopper [protected]

lemur::api::ScoreAccumulator* lemur::retrieval::XLingRetMethod::termScores [protected]

The documentation for this class was generated from the following files:
Generated on Tue Jun 15 11:03:07 2010 for Lemur by doxygen 1.3.4