A class to read one line at a time from a backing file, and tokenize that line based on whitespace, and then interpret each token as a feature-value pair via a protected method ExtractFeatureValuePair (see the documentation for that method for details on how tokens are interpreted as feature-value pairs). More...

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

Inheritance diagram for reranker::BasicFileBackedFeatureExtractor:

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

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

virtual void	Extract (Candidate &candidate, FeatureVector< int, double > &features)
	Does nothing. More...

virtual void	ExtractSymbolic (Candidate &candidate, FeatureVector< string, double > &symbolic_features)
	Extracts symbolic features based on the most recent line read from the file (or stream) that backs this feature extractor. More...

Public Member Functions inherited from reranker::AbstractFileBackedFeatureExtractor
	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	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	ExtractFeatureValuePair (const string &s, string &feature, double &value)
	Extracts a symbolic feature and value from the specified string. More...

Protected Member Functions inherited from reranker::AbstractFileBackedFeatureExtractor
virtual void	ReadFromStream ()
	Reads from the stream. More...

Additional Inherited Members
Protected Attributes inherited from reranker::AbstractFileBackedFeatureExtractor
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

A class to read one line at a time from a backing file, and tokenize that line based on whitespace, and then interpret each token as a feature-value pair via a protected method ExtractFeatureValuePair (see the documentation for that method for details on how tokens are interpreted as feature-value pairs).

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

Constructor & Destructor Documentation

reranker::BasicFileBackedFeatureExtractor::BasicFileBackedFeatureExtractor ( )

inline

Constructs an instance.

Definition at line 61 of file basic-file-backed-feature-extractor.H.

virtual reranker::BasicFileBackedFeatureExtractor::~BasicFileBackedFeatureExtractor ( )

inlinevirtual

Destroys this instance.

Definition at line 64 of file basic-file-backed-feature-extractor.H.

Member Function Documentation

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

inlinevirtual

Does nothing.

Implements reranker::AbstractFileBackedFeatureExtractor.

Reimplemented in reranker::FileBackedNgramFeatureExtractor.

Definition at line 67 of file basic-file-backed-feature-extractor.H.

virtual void reranker::BasicFileBackedFeatureExtractor::ExtractFeatureValuePair	(	const string &	s,
		string &	feature,
		double &	value
	)

inlineprotectedvirtual

Extracts a symbolic feature and value from the specified string.

The specified string may have one of three forms:

String	Feature name	Feature weight
`foo`	`foo`	`1.0`
`foo=`	`foo`	`1.0`
`foo=value`	`foo`	`value`

where value is the (string representation of) a floating-point value.

Parameters

[in]	s	the string from which to extract a feature-value pair
[out]	feature	the symbolic feature name extracted from the specified string `s`
[out]	value	the symbolic feature’s value extracted from the specified string `s`

Definition at line 97 of file basic-file-backed-feature-extractor.H.

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

virtual

Extracts symbolic features based on the most recent line read from the file (or stream) that backs this feature extractor.

The line is tokenized based on whitespace, and each token is transformed into a feature-value pair via the ExtractFeatureValuePair method.

Implements reranker::AbstractFileBackedFeatureExtractor.

Reimplemented in reranker::FileBackedNgramFeatureExtractor.

Definition at line 43 of file basic-file-backed-feature-extractor.C.

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

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation