lemur::retrieval::PassageRep Class Reference

Passage representation for a document. More...

#include <PassageRep.hpp>

Inheritance diagram for lemur::retrieval::PassageRep:

List of all members.

Public Member Functions
	PassageRep (lemur::api::DocumentRep &dRep, int d, int p, int o)
	Fixed sized window passage with overlap.
PassageRep::iterator	begin ()
PassageRep::iterator	end ()
void	setEnd (int s, int e, int dl)
	update end and length values
int	passageTF (lemur::api::TERMID_T tid, lemur::api::MatchInfo *matches) const
	Term frequency of a term within the current passage.
int	getStart () const
	start of the current passage
int	getEnd () const
	end + 1 of the current passage
virtual double	termWeight (lemur::api::TERMID_T termID, const lemur::api::DocInfo *info) const
	Delegate call to termWeight of the encapsulated DocumentRep.
virtual double	scoreConstant () const
	Delegate call to scoreConstant of the encapsulated DocumentRep.
Protected Attributes
lemur::api::DocumentRep &	docRep
	DocumentRep for the whole document. Calls to termWeight and scoreConstant are delegated to it.
int	psgSize
	Size of the passage, in number of tokens.
int	overlap
	Number of tokens to overlap when advancing the passage window.
int	docEnd
	Length of the whole document.
int	start
	index of start of the current passage.
int	pEnd
	index of end of the current passage.

---

Detailed Description

Passage representation for a document.

Supports iteration over passages of fixed window size with an overlap of K terms for the window. Encapsulates the DocumentRep for the whole document, modifying its docLength attribute. Delegates calls to termWeight and scoreConstant to the encapsulated DocumentRep. TFIDFRetMethod with BM25 tf weighting and OkapiRetMethod will not compute correct scores, as they use the average document length from the collection in their formulas. The difference should be small.

---

Constructor & Destructor Documentation

lemur::retrieval::PassageRep::PassageRep (  lemur::api::DocumentRep &  dRep, int  d, int  p, int  o )  [inline]

Fixed sized window passage with overlap. Parameters: dRep  DocumentRep for the document as returned by computeDocRep. d  length of whole document. p  size of passage in terms of tokens. o  number of tokens to overlap.

---

Member Function Documentation

PassageRep::iterator lemur::retrieval::PassageRep::begin (   )  [inline]

PassageRep::iterator lemur::retrieval::PassageRep::end (   )  [inline]

int lemur::retrieval::PassageRep::getEnd (   )  const [inline]

end + 1 of the current passage

int lemur::retrieval::PassageRep::getStart (   )  const [inline]

start of the current passage

int lemur::retrieval::PassageRep::passageTF (  lemur::api::TERMID_T  tid, lemur::api::MatchInfo *  matches )  const [inline]

Term frequency of a term within the current passage. Parameters: tid  the term id to count. matches  the term matches returned by MatchInfo::getMatches for the document. This list is used for efficiency, as it is shorter than the whole TermInfoList for the document. Returns: the frequency of a term within the current passage.

virtual double lemur::retrieval::PassageRep::scoreConstant (   )  const [inline, virtual]

Delegate call to scoreConstant of the encapsulated DocumentRep. Implements lemur::api::DocumentRep.

void lemur::retrieval::PassageRep::setEnd (  int  s, int  e, int  dl )  [inline]

update end and length values

virtual double lemur::retrieval::PassageRep::termWeight (  lemur::api::TERMID_T  termID, const lemur::api::DocInfo *  info )  const [inline, virtual]

Delegate call to termWeight of the encapsulated DocumentRep.

---

Member Data Documentation

int lemur::retrieval::PassageRep::docEnd [mutable, protected]

Length of the whole document.

lemur::api::DocumentRep& lemur::retrieval::PassageRep::docRep [protected]

DocumentRep for the whole document. Calls to termWeight and scoreConstant are delegated to it.

int lemur::retrieval::PassageRep::overlap [protected]

Number of tokens to overlap when advancing the passage window.

int lemur::retrieval::PassageRep::pEnd [mutable, protected]

index of end of the current passage.

int lemur::retrieval::PassageRep::psgSize [protected]

Size of the passage, in number of tokens.

int lemur::retrieval::PassageRep::start [mutable, protected]

index of start of the current passage.

---

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

• PassageRep.hpp

---