edu.stanford.nlp.ie
Class UniformPrior<IN extends CoreMap>

java.lang.Object
  edu.stanford.nlp.ie.UniformPrior<IN>

All Implemented Interfaces:

SequenceListener, SequenceModel

public class UniformPrior<IN extends CoreMap>
extends java.lang.Object
implements SequenceModel, SequenceListener

Uniform prior to be used for generic Gibbs inference in the ie.crf.CRFClassifier

Author:

Mihai

Field Summary

protected int	backgroundSymbol
protected Index<java.lang.String>	classIndex
protected java.util.List<IN>	doc
protected int	numClasses
protected int[]	possibleValues
protected int[]	sequence

Constructor Summary

UniformPrior(java.lang.String backgroundSymbol, Index<java.lang.String> classIndex, java.util.List<IN> doc)

Method Summary

int[]	getPossibleValues(int position) 0...leftWindow-1 etc are null, leftWindow...length+leftWindow-1 are words, length+leftWindow...length+leftWindow+rightWindow-1 are null;
int	leftWindow() How many positions to the left a position is dependent on.
int	length()
int	rightWindow() How many positions to the right a position is dependent on.
double	scoreOf(int[] sequence) Computes the score assigned by this model to the whole sequence.
double	scoreOf(int[] sequence, int position) Computes the unnormalized log conditional distribution over values of the element at position pos in the sequence, conditioned on the values of the elements in all other positions of the provided sequence.
double[]	scoresOf(int[] sequence, int position) Computes the unnormalized log conditional distribution over values of the element at position pos in the sequence, conditioned on the values of the elements in all other positions of the provided sequence.
void	setInitialSequence(int[] sequence) Informs this sequence listener that the value of the whole sequence is initialized to sequence
void	updateSequenceElement(int[] sequence, int pos, int oldVal) Informs this sequence listener that the value of the element at position pos has changed.

Methods inherited from class java.lang.Object

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

Field Detail

sequence

protected int[] sequence

backgroundSymbol

protected int backgroundSymbol

numClasses

protected int numClasses

possibleValues

protected int[] possibleValues

classIndex

protected Index<java.lang.String> classIndex

doc

protected java.util.List<IN extends CoreMap> doc

Constructor Detail

UniformPrior

public UniformPrior(java.lang.String backgroundSymbol,
                    Index<java.lang.String> classIndex,
                    java.util.List<IN> doc)

Method Detail

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 to compute a score for

Returns:

the score for the sequence

scoresOf

public double[] scoresOf(int[] sequence,
                         int position)

Description copied from interface: SequenceModel

Computes the unnormalized log conditional distribution over values of the element at position pos in the sequence, conditioned on the values of the elements in all other positions of the provided sequence.

Specified by:

scoresOf in interface SequenceModel

Parameters:

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

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

Returns:

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

getPossibleValues

public int[] getPossibleValues(int position)

Description copied from interface: SequenceModel

0...leftWindow-1 etc are null, leftWindow...length+leftWindow-1 are words, length+leftWindow...length+leftWindow+rightWindow-1 are null;

Specified by:

getPossibleValues in interface SequenceModel

Parameters:

position - the position

Returns:

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

leftWindow

public int leftWindow()

Description copied from interface: SequenceModel

How many positions to the left a position is dependent on.

Specified by:

leftWindow in interface SequenceModel

Returns:

the size of the left window used by this sequence model

length

public int length()

Specified by:

length in interface SequenceModel

Returns:

the length of the sequences modeled by this SequenceModel

rightWindow

public int rightWindow()

Description copied from interface: SequenceModel

How many positions to the right a position is dependent on.

Specified by:

rightWindow in interface SequenceModel

Returns:

the size of the right window used by this sequence model

scoreOf

public double scoreOf(int[] sequence,
                      int position)

Description copied from interface: SequenceModel

Computes the unnormalized log conditional distribution over values of the element at position pos in the sequence, conditioned on the values of the elements in all other positions of the provided sequence.

Specified by:

scoreOf in interface SequenceModel

Parameters:

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

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

Returns:

the log score of the token at the specified position in the sequence

setInitialSequence

public void setInitialSequence(int[] sequence)

Description copied from interface: SequenceListener

Informs this sequence listener that the value of the whole sequence is initialized to sequence

Specified by:

setInitialSequence in interface SequenceListener

updateSequenceElement

public void updateSequenceElement(int[] sequence,
                                  int pos,
                                  int oldVal)

Description copied from interface: SequenceListener

Informs this sequence listener that the value of the element at position pos has changed. This allows this sequence model to update its internal model if desired.

Specified by:

updateSequenceElement in interface SequenceListener