CRFSuite::Tagger Class Reference

The tagger class. More...

List of all members.

Public Member Functions
	Tagger ()
	Construct a tagger.
virtual	~Tagger ()
	Destruct a tagger.
bool	open (const std::string &name)
	Open a model file.
void	close ()
	Close the model.
StringList	labels ()
	Obtain the list of labels.
StringList	tag (const ItemSequence &xseq)
	Predict the label sequence for the item sequence.
void	set (const ItemSequence &xseq)
	Set an item sequence.
StringList	viterbi ()
	Find the Viterbi label sequence for the item sequence.
double	probability (const StringList &yseq)
	Compute the probability of the label sequence.
double	marginal (const std::string &y, const int t)
	Compute the marginal probability of the label.

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Detailed Description

The tagger class.

This class provides the functionality for predicting label sequences for input sequences using a model.

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Member Function Documentation

StringList CRFSuite::Tagger::labels

(

)

Obtain the list of labels.

Returns:

StringList The list of labels in the model.

Exceptions:

std::invalid_argument	A model is not opened.
std::runtime_error	An internal error.

double CRFSuite::Tagger::marginal	(	const std::string &	y,
		const int	t
	)

Compute the marginal probability of the label.

Parameters:

y	The label.
t	The position of the label.

Exceptions:

std::invalid_argument	A model is not opened.
std::runtime_error	An internal error.

bool CRFSuite::Tagger::open

(

const std::string &

name

)

Open a model file.

Parameters:

name	The file name of the model file.

Returns:

bool true if the model file is successfully opened, false otherwise (e.g., when the mode file is not found).

Exceptions:

std::runtime_error

An internal error in the model.

double CRFSuite::Tagger::probability

(

const StringList &

yseq

)

Compute the probability of the label sequence.

Parameters:

yseq	The label sequence.

Exceptions:

std::invalid_argument	A model is not opened.
std::runtime_error	An internal error.

void CRFSuite::Tagger::set

(

const ItemSequence &

xseq

)

Set an item sequence.

This function sets an item sequence for future calls for viterbi(), probability(), and marginal() functions.

Parameters:

xseq	The item sequence to be tagged

Exceptions:

std::invalid_argument	A model is not opened.
std::runtime_error	An internal error.

StringList CRFSuite::Tagger::tag

(

const ItemSequence &

xseq

)

Predict the label sequence for the item sequence.

This function calls set() and viterbi() functions to obtain the label sequence predicted for the item sequence.

Parameters:

xseq	The item sequence to be tagged.

Returns:

StringList The label sequence predicted.

Exceptions:

std::invalid_argument	A model is not opened.
std::runtime_error	An internal error.

StringList CRFSuite::Tagger::viterbi

(

)

Find the Viterbi label sequence for the item sequence.

Returns:

StringList The label sequence predicted.

Exceptions:

std::invalid_argument	A model is not opened.
std::runtime_error	An internal error.