uk.ac.gla.dcs.renaissance.iqir.query
Class RFOperator

java.lang.Object
  uk.ac.gla.dcs.renaissance.iqir.query.RFOperator

All Implemented Interfaces:

Operator

public class RFOperator
extends Object
implements Operator

An operator based on relevance feedback data. It creates a ranking, based on the given scorer function, w.r.t. the given query. From the top k documents it extracts the IN vectors and creates a density out of it.

Author:

Ingo Frommholz

Constructor Summary

RFOperator(String scorer, String query, int k)

Method Summary

void	addINSamplingQueries(Set<String> set) Add the queries that will be used to compute base densities.
void	addTerms(Set<String> set) Add the terms
void	applyToSuboperators(OperatorTransformer transformer) Apply the transformation to all sub-operators
WeightedVectorSet	compute(boolean needsSum, bpiwowar.log.TaskTimer timer) Computes the density.
Operator	copy() Deep copy of this operator
Iterable<Operator>	getSubOperators() Get all the suboperators (used to process recursively all the nodes of a query).
void	init(Informations informations) Initialise this operator so as to prepare computation
boolean	isNull() Returns true if the density is null (e.g., stopped term).
Operator	simplify() Simplify this operator (calls simplify recursively).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RFOperator

public RFOperator(String scorer,
                  String query,
                  int k)

Parameters:

scorer - the scorer to use, e.g. "BM25"

query - the query in a format understood by the scorer

k - take the top k documents for relevance feedback

Method Detail

init

public void init(Informations informations)

Description copied from interface: Operator

Initialise this operator so as to prepare computation

Specified by:

init in interface Operator

addINSamplingQueries

public void addINSamplingQueries(Set<String> set)

Description copied from interface: Operator

Add the queries that will be used to compute base densities. The syntax of the queries can be found in in the MG4J API.

Specified by:

addINSamplingQueries in interface Operator

Parameters:

set - The base queries should be added to this set

compute

public WeightedVectorSet compute(boolean needsSum,
                                 bpiwowar.log.TaskTimer timer)
                          throws Throwable

Description copied from interface: Operator

Computes the density. The object will be first initialised with Operator.init(Informations)

Specified by:

compute in interface Operator

Parameters:

needsSum - If the sum of vectors is needed

timer - A timer to give information about the task progress

Returns:

A density with the sum

Throws:

Throwable - if something goes wrong

isNull

public boolean isNull()

Description copied from interface: Operator

Returns true if the density is null (e.g., stopped term). The object should have been initialised before with Operator.init(Informations)

Specified by:

isNull in interface Operator

simplify

public Operator simplify()

Description copied from interface: Operator

Simplify this operator (calls simplify recursively). The object should be initialised with Operator.init(Informations)

Specified by:

simplify in interface Operator

addTerms

public void addTerms(Set<String> set)

Description copied from interface: Operator

Add the terms

Specified by:

addTerms in interface Operator

Parameters:

set - The set of terms

getSubOperators

public Iterable<Operator> getSubOperators()

Description copied from interface: Operator

Get all the suboperators (used to process recursively all the nodes of a query). No special order is expected between nodes.

Specified by:

getSubOperators in interface Operator

copy

public Operator copy()

Description copied from interface: Operator

Deep copy of this operator

Specified by:

copy in interface Operator

applyToSuboperators

public void applyToSuboperators(OperatorTransformer transformer)

Description copied from interface: Operator

Apply the transformation to all sub-operators

Specified by:

applyToSuboperators in interface Operator