This class makes it easy for concrete subclasses to extract features based on input from a file. More...

#include <abstract-file-backed-feature-extractor.H>

Inheritance diagram for reranker::AbstractFileBackedFeatureExtractor:

Public Member Functions
	AbstractFileBackedFeatureExtractor ()
	Constructs an instance. More...

virtual	~AbstractFileBackedFeatureExtractor ()
	Destroys this instance. More...

virtual void	RegisterInitializers (Initializers &initializers)
	Registers the data member to be initialized when an instance of this class is constructed by a Factory. More...

virtual void	Init (const Environment *env, const string &arg)
	This method is guaranteed to be inokved by a Factory after invoking the RegisterInitializers method just after construction. More...

virtual void	Extract (Candidate &candidate, FeatureVector< int, double > &features)=0
	Extracts features for the specified candidate, where each feature is represented by an int for its unique identifier. More...

virtual void	ExtractSymbolic (Candidate &candidate, FeatureVector< string, double > &symbolic_features)=0
	Extracts symbolic features for the specified candidate, where each feature is represented by a string for its unique identifier. More...

virtual void	Reset ()
	Indicates to this instance that iteration over candidate sets on which features are being extracted has been reset. More...

virtual void	Extract (CandidateSet &candidate_set)
	Extracts features for all the candidates in the specified CandidateSet. More...

virtual long	line_number () const
	Returns the current number of lines read by this feature extractor from the underlying stream. More...

Public Member Functions inherited from reranker::FeatureExtractor
	FeatureExtractor ()
	Constructs an empty feature vector. More...

virtual	~FeatureExtractor ()
	Destroys this vector. More...

Public Member Functions inherited from reranker::FactoryConstructible
virtual	~FactoryConstructible ()

Protected Member Functions
virtual void	ReadFromStream ()
	Reads from the stream. More...

Protected Attributes
string	filename_
	The name of the file backing this feature extractor. More...

istream *	is_
	The stream created from the file backing this feature extractor. More...

string	line_
	The last line read by this feature extractor. More...

long	line_number_
	The number of lines read so far by this feature extractor. More...

Tokenizer	tokenizer_
	A simple whitespace tokenizer for use by concrete subclasses. More...

Detailed Description

This class makes it easy for concrete subclasses to extract features based on input from a file.

Definition at line 57 of file abstract-file-backed-feature-extractor.H.

Constructor & Destructor Documentation

reranker::AbstractFileBackedFeatureExtractor::AbstractFileBackedFeatureExtractor ( )

inline

Constructs an instance.

Definition at line 60 of file abstract-file-backed-feature-extractor.H.

virtual reranker::AbstractFileBackedFeatureExtractor::~AbstractFileBackedFeatureExtractor ( )

inlinevirtual

Destroys this instance.

Definition at line 63 of file abstract-file-backed-feature-extractor.H.

Member Function Documentation

virtual void reranker::AbstractFileBackedFeatureExtractor::Extract	(	Candidate &	candidate,
		FeatureVector< int, double > &	features
	)

pure virtual

Extracts features for the specified candidate, where each feature is represented by an int for its unique identifier.

Implementation advice:: Please play nice with others! For efficiency, the feature vector you are modifying is the actual feature vector inside the specified Candidate. Please use FeatureVector::IncrementWeight wherever possible; only use FeatureVector::SetWeight if you truly want to blow away any existing weight for a feature.

Parameters

[in]	candidate	the candidate for which to extract features
[out]	features	the features extracted for the specified candidate

Implements reranker::FeatureExtractor.

Implemented in reranker::FileBackedNgramFeatureExtractor, reranker::FileBackedLossSetter, and reranker::BasicFileBackedFeatureExtractor.

virtual void reranker::AbstractFileBackedFeatureExtractor::Extract ( CandidateSet & candidate_set )

inlinevirtual

Extracts features for all the candidates in the specified CandidateSet.

The default implementation here uses the concrete implementations of the Extract(Candidate&,FeatureVector<int,double>&) and ExtractSymbolic methods.

Parameters

candidate_set the set of candidates for which to extract features.

Reimplemented from reranker::FeatureExtractor.

Definition at line 127 of file abstract-file-backed-feature-extractor.H.

virtual void reranker::AbstractFileBackedFeatureExtractor::ExtractSymbolic	(	Candidate &	candidate,
		FeatureVector< string, double > &	symbolic_features
	)

pure virtual

Extracts symbolic features for the specified candidate, where each feature is represented by a string for its unique identifier.

Implementation advice:: Please play nice with others! For efficiency, the feature vector you are modifying is the actual feature vector inside the specified Candidate. Please use FeatureVector::IncrementWeight wherever possible; only use FeatureVector::SetWeight if you truly want to blow away any existing weight for a feature.

Parameters

[in]	candidate	the candidate for which to extract features
[out]	symbolic_features	the features extracted for the specified candidate

Implements reranker::FeatureExtractor.

Implemented in reranker::FileBackedNgramFeatureExtractor, reranker::FileBackedLossSetter, and reranker::BasicFileBackedFeatureExtractor.

virtual void reranker::AbstractFileBackedFeatureExtractor::Init	(	const Environment *	env,
		const string &	arg
	)

inlinevirtual

This method is guaranteed to be inokved by a Factory after invoking the RegisterInitializers method just after construction.

Parameters

env	the environment just after initializing this object
arg	the string parsed by the Factory

See Also: Factory::CreateOrDie

Reimplemented from reranker::FactoryConstructible.

Reimplemented in reranker::FileBackedLossSetter.

Definition at line 99 of file abstract-file-backed-feature-extractor.H.

virtual long reranker::AbstractFileBackedFeatureExtractor::line_number ( ) const

inlinevirtual

Returns the current number of lines read by this feature extractor from the underlying stream.

Definition at line 140 of file abstract-file-backed-feature-extractor.H.

virtual void reranker::AbstractFileBackedFeatureExtractor::ReadFromStream ( )

inlineprotectedvirtual

Reads from the stream.

The default implementation here reads a single line and puts it into the protected line_ member.

Definition at line 145 of file abstract-file-backed-feature-extractor.H.

virtual void reranker::AbstractFileBackedFeatureExtractor::RegisterInitializers ( Initializers & initializers )

inlinevirtual

Registers the data member to be initialized when an instance of this class is constructed by a Factory.

Variable name	Type	Required	Description	Default value
`filename`	`string`	Yes	The name of the file backing this feature extractor.	n/a

Reimplemented from reranker::FactoryConstructible.

Reimplemented in reranker::FileBackedNgramFeatureExtractor, and reranker::FileBackedLossSetter.

Definition at line 86 of file abstract-file-backed-feature-extractor.H.

virtual void reranker::AbstractFileBackedFeatureExtractor::Reset ( )

inlinevirtual

Indicates to this instance that iteration over candidate sets on which features are being extracted has been reset.

Concrete subclasses should override this method (which by default does nothing) if they need to do something special at the beginning of each iteration.

Reimplemented from reranker::FeatureExtractor.

Definition at line 113 of file abstract-file-backed-feature-extractor.H.