Class for calculating ESet term weights. More...

#include <expandweight.h>

Inheritance diagram for Xapian::Internal::ExpandWeight:

Collaboration diagram for Xapian::Internal::ExpandWeight:

Public Member Functions
	ExpandWeight (const Xapian::Database &db_, Xapian::doccount rsize_, bool use_exact_termfreq_, bool want_collection_freq_)
	Constructor. More...

	ExpandWeight (const Xapian::Database &db_, Xapian::doccount rsize_, bool use_exact_termfreq_, bool want_collection_freq_, double expand_k_)
	Constructor. More...

void	collect_stats (TermList *merger, const std::string &term)
	Get the term statistics. More...

virtual double	get_weight () const =0
	Calculate the weight. More...

Protected Member Functions
double	get_avlen () const
	Return the average length of the database. More...

Xapian::doccount	get_rsize () const
	Return the number of documents in the RSet. More...

Xapian::termcount	get_collection_freq () const
	Return the collection frequency of the term. More...

Xapian::totallength	get_collection_len () const
	Return the length of the collection. More...

Xapian::doccount	get_dbsize () const
	Return the size of the database. More...

Protected Attributes
ExpandStats	stats
	An ExpandStats object to accumulate statistics. More...

Private Attributes
const Xapian::Database	db
	The combined database. More...

Xapian::doccount	dbsize
	The number of documents in the whole database. More...

Xapian::doclength	avlen
	Average document length in the whole database. More...

Xapian::doccount	rsize
	The number of documents in the RSet. More...

Xapian::termcount	collection_freq
	The collection frequency of the term. More...

Xapian::totallength	collection_len
	The total length of the database. More...

bool	use_exact_termfreq
	Should we calculate the exact term frequency when generating an ESet? More...

bool	want_collection_freq
	Does the expansion scheme use collection frequency? More...

Detailed Description

Class for calculating ESet term weights.

Definition at line 114 of file expandweight.h.

Constructor & Destructor Documentation

◆ ExpandWeight() [1/2]

Xapian::Internal::ExpandWeight::ExpandWeight	(	const Xapian::Database &	db_,
		Xapian::doccount	rsize_,
		bool	use_exact_termfreq_,
		bool	want_collection_freq_
	)

inline

Constructor.

Parameters

db_	The database.
rsize_	The number of documents in the RSet.
use_exact_termfreq_	When expanding over a combined database, should we use the exact termfreq (if false a cheaper approximation is used).

Definition at line 157 of file expandweight.h.

◆ ExpandWeight() [2/2]

Xapian::Internal::ExpandWeight::ExpandWeight	(	const Xapian::Database &	db_,
		Xapian::doccount	rsize_,
		bool	use_exact_termfreq_,
		bool	want_collection_freq_,
		double	expand_k_
	)

inline

Constructor.

Parameters

db_	The database.
rsize_	The number of documents in the RSet.
use_exact_termfreq_	When expanding over a combined database, should we use the exact termfreq (if false a cheaper approximation is used).
expand_k_	The parameter for TradWeight query expansion.

Definition at line 177 of file expandweight.h.

Member Function Documentation

◆ collect_stats()

void Xapian::Internal::ExpandWeight::collect_stats	(	TermList *	merger,
		const std::string &	term
	)

Get the term statistics.

Parameters

merger	The tree of TermList objects.
term	The current term name.

Definition at line 37 of file expandweight.cc.

References Xapian::TermIterator::Internal::accumulate_stats(), AssertEqParanoid, AssertRel, LOGCALL_VOID, LOGLINE, and LOGVALUE.

Referenced by Xapian::ESet::Internal::expand().

◆ get_avlen()

double Xapian::Internal::ExpandWeight::get_avlen ( ) const

inlineprotected

Return the average length of the database.

Definition at line 203 of file expandweight.h.

References Xapian::Internal::ExpandStats::avlen.

◆ get_collection_freq()

Xapian::termcount Xapian::Internal::ExpandWeight::get_collection_freq ( ) const

inlineprotected

Return the collection frequency of the term.

Definition at line 209 of file expandweight.h.

◆ get_collection_len()

Xapian::totallength Xapian::Internal::ExpandWeight::get_collection_len ( ) const

inlineprotected

Return the length of the collection.

Definition at line 212 of file expandweight.h.

◆ get_dbsize()

Xapian::doccount Xapian::Internal::ExpandWeight::get_dbsize ( ) const

inlineprotected

Return the size of the database.

Definition at line 215 of file expandweight.h.

References Xapian::Internal::ExpandStats::dbsize.

◆ get_rsize()

Xapian::doccount Xapian::Internal::ExpandWeight::get_rsize ( ) const

inlineprotected

Return the number of documents in the RSet.

Definition at line 206 of file expandweight.h.

◆ get_weight()

virtual double Xapian::Internal::ExpandWeight::get_weight ( ) const

pure virtual

Calculate the weight.

Implemented in Xapian::Internal::Bo1EWeight, and Xapian::Internal::TradEWeight.

Referenced by Xapian::ESet::Internal::expand().

Member Data Documentation

◆ avlen

Xapian::doclength Xapian::Internal::ExpandWeight::avlen

private

Average document length in the whole database.

Definition at line 122 of file expandweight.h.

◆ collection_freq

Xapian::termcount Xapian::Internal::ExpandWeight::collection_freq

private

The collection frequency of the term.

Definition at line 128 of file expandweight.h.

◆ collection_len

Xapian::totallength Xapian::Internal::ExpandWeight::collection_len

private

The total length of the database.

Definition at line 131 of file expandweight.h.

◆ db

const Xapian::Database Xapian::Internal::ExpandWeight::db

private

The combined database.

Definition at line 116 of file expandweight.h.

◆ dbsize

Xapian::doccount Xapian::Internal::ExpandWeight::dbsize

private

The number of documents in the whole database.

Definition at line 119 of file expandweight.h.

◆ rsize

Xapian::doccount Xapian::Internal::ExpandWeight::rsize

private

The number of documents in the RSet.

Definition at line 125 of file expandweight.h.

◆ stats

ExpandStats Xapian::Internal::ExpandWeight::stats

protected

An ExpandStats object to accumulate statistics.

Definition at line 200 of file expandweight.h.

◆ use_exact_termfreq

bool Xapian::Internal::ExpandWeight::use_exact_termfreq

private

Should we calculate the exact term frequency when generating an ESet?

This only has any effect if we're using a combined database.

If this member is true, the exact term frequency will be obtained from the Database object. If this member is false, then an approximation is used to estimate the term frequency based on the term frequencies in the sub-databases which we see while collating term statistics, and the relative sizes of the sub-databases.

Definition at line 143 of file expandweight.h.

◆ want_collection_freq

bool Xapian::Internal::ExpandWeight::want_collection_freq

private

Does the expansion scheme use collection frequency?

Definition at line 146 of file expandweight.h.

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

expand/expandweight.h
expand/expandweight.cc

Public Member Functions

Protected Member Functions

Protected Attributes

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ ExpandWeight() [1/2]

◆ ExpandWeight() [2/2]

Member Function Documentation

◆ collect_stats()

◆ get_avlen()

◆ get_collection_freq()

◆ get_collection_len()

◆ get_dbsize()

◆ get_rsize()

◆ get_weight()

Member Data Documentation

◆ avlen

◆ collection_freq

◆ collection_len

◆ db

◆ dbsize

◆ rsize

◆ stats

◆ use_exact_termfreq

◆ want_collection_freq