edu.stanford.nlp.ie.crf

Class TestSequenceModel

java.lang.Object

edu.stanford.nlp.ie.crf.TestSequenceModel

All Implemented Interfaces:

SequenceModel

public class TestSequenceModel
extends Object
implements SequenceModel

For sequence model inference at test-time.

Author:

Spence Green

Constructor Summary

Constructors

Constructor and Description
TestSequenceModel(CRFCliqueTree<? extends CharSequence> cliqueTree)
TestSequenceModel(CRFCliqueTree<? extends CharSequence> cliqueTree, LabelDictionary labelDictionary, List<? extends CoreMap> document)

Method Summary

Modifier and Type	Method and Description
int[]	getPossibleValues(int pos) Return the valid sequence labels (as integer indices) for a particular position in the sequence.
int	leftWindow() How many label positions to the left influence the label assignment at a particular position.
int	length()
int	rightWindow() How many label positions to the right influence the label assignment at a particular position.
double	scoreOf(int[] sequence) Computes the score assigned by this model to the whole sequence.
double	scoreOf(int[] tags, int pos) Return the score of the proposed tags for position given.
double[]	scoresOf(int[] tags, int pos) Computes the scores of labels for the element at the given position in the sequence, conditioned on the values of the labels at all other positions of the provided sequence.

Methods inherited from class java.lang.Object

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

Constructor Detail

TestSequenceModel

public TestSequenceModel(CRFCliqueTree<? extends CharSequence> cliqueTree)

TestSequenceModel

public TestSequenceModel(CRFCliqueTree<? extends CharSequence> cliqueTree,
                         LabelDictionary labelDictionary,
                         List<? extends CoreMap> document)

Method Detail

length

public int length()

Specified by:

length in interface SequenceModel

Returns:

The length of the sequences modeled by this SequenceModel. This is its real length, not including the leftWindow() + rightWindow() of extra padding positions.

leftWindow

public int leftWindow()

Description copied from interface: SequenceModel

How many label positions to the left influence the label assignment at a particular position.

Specified by:

leftWindow in interface SequenceModel

Returns:

The size of the left window used by this sequence model

rightWindow

public int rightWindow()

Description copied from interface: SequenceModel

How many label positions to the right influence the label assignment at a particular position.

Specified by:

rightWindow in interface SequenceModel

Returns:

the size of the right window used by this sequence model

getPossibleValues

public int[] getPossibleValues(int pos)

Description copied from interface: SequenceModel

Return the valid sequence labels (as integer indices) for a particular position in the sequence. Since the sequence is padded at each end, typically sequence items 0...leftWindow-1 are null, leftWindow...length+leftWindow-1 are words, length+leftWindow...length+leftWindow+rightWindow-1 are null.

Specified by:

getPossibleValues in interface SequenceModel

Parameters:

pos - The position

Returns:

The set of possible int values at this position, as an int array

scoreOf

public double scoreOf(int[] tags,
                      int pos)

Return the score of the proposed tags for position given.

Specified by:

scoreOf in interface SequenceModel

Parameters:

tags - is an array indicating the assignment of labels to score.

pos - is the position to return a score for.

Returns:

The score of the label at the specified position in the sequence

scoresOf

public double[] scoresOf(int[] tags,
                         int pos)

Description copied from interface: SequenceModel

Computes the scores of labels for the element at the given position in the sequence, conditioned on the values of the labels at all other positions of the provided sequence. The returned array elements correspond index-by-index to the possible values returned by getPossibleValues(int). The label at sequence[position] is ignored in the calculations. The scores are often given as an unnormalized log conditional distribution over possible labels. Otherwise, they may be probabilities. If it is a probability distribution, conceptually, the scores should sum to 1 (perhaps after transforming them). Note that implementations often alter sequence[position] to do their calculations, and so access to the array isn't threadsafe, but should restore its value afterwards.

Specified by:

scoresOf in interface SequenceModel

Parameters:

tags - The sequence containing the rest of the values to condition on

pos - The position of the element to give a distribution for

Returns:

The scores of the possible tokens at the specified position in the sequence

scoreOf

public double scoreOf(int[] sequence)

Description copied from interface: SequenceModel

Computes the score assigned by this model to the whole sequence. Typically this will be an unnormalized probability in log space (since the probabilities are small).

Specified by:

scoreOf in interface SequenceModel

Parameters:

sequence - The sequence of labels to compute a score for

Returns:

The score for the entire sequence