edu.umass.cs.mallet.base.types

Class Multinomial

java.lang.Object

edu.umass.cs.mallet.base.types.SparseVector

edu.umass.cs.mallet.base.types.FeatureVector

edu.umass.cs.mallet.base.types.Multinomial

All Implemented Interfaces:

ConstantMatrix, Vector, Serializable

Direct Known Subclasses:

Multinomial.Logged

public class Multinomial
extends FeatureVector

A probability distribution over a set of features represented as a FeatureVector. The values associated with each element in the Multinomial/FeaturVector are probabilities and should sum to 1. Features are indexed using feature indices - the index into the underlying Alphabet - rather than using locations the way FeatureVectors do.

Multinomial.Estimator provides a subhierachy of ways to generate an estimate of the probability distribution from counts associated with the features.

Author:

Andrew McCallum mccallum@cs.umass.edu

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Multinomial.Estimator A hierarchy of classes used to produce estimates of probabilities, in the form of a Multinomial, from counts associated with the elements of an Alphabet.
static class	Multinomial.LaplaceEstimator An MEstimator with m set to 1.
static class	Multinomial.Logged A Multinomial in which the values associated with each feature index fi is Math.log(probability[fi]) instead of probability[fi].
static class	Multinomial.MAPEstimator Unimplemented, but the MEstimators are.
static class	Multinomial.MEstimator An Estimator in which probability estimates in a Multinomial are generated by adding a constant m (specified at construction time) to each count before dividing by the total of the m-biased counts.
static class	Multinomial.MLEstimator An MEstimator with m set to 0.

Field Summary

Fields inherited from class edu.umass.cs.mallet.base.types.SparseVector

hasInfinite, indices, values

Constructor Summary

Constructors

Modifier	Constructor and Description
	Multinomial(double[] probabilities)
	Multinomial(double[] probabilities, Alphabet dictionary)
protected	Multinomial(double[] probabilities, Alphabet dictionary, int size, boolean copy, boolean checkSum)
	Multinomial(double[] probabilities, int size)

Method Summary

Modifier and Type	Method and Description
void	addProbabilitiesTo(double[] vector)
Alphabet	getAlphabet()
double	logProbability(int featureIndex)
double	logProbability(Object key)
double	probability(int featureIndex)
double	probability(Object key)
FeatureSequence	randomFeatureSequence(Random r, int length)
FeatureVector	randomFeatureVector(Random r, int size)
int	randomIndex(Random r)
Object	randomObject(Random r)
int	size()

Methods inherited from class edu.umass.cs.mallet.base.types.FeatureVector

cloneMatrix, cloneMatrixZeroed, contains, getObjectIndices, location, toSimpFile, toString, toString, value

Methods inherited from class edu.umass.cs.mallet.base.types.SparseVector

absNorm, addTo, addTo, arrayCopyFrom, arrayCopyFrom, arrayCopyInto, dotProduct, dotProduct, dotProduct, dotProduct, extendedDotProduct, extendedDotProduct, getDimensions, getIndices, getNumDimensions, getValues, incrementValue, indexAtLocation, infinityNorm, isBinary, isNaN, location, makeBinary, makeNonBinary, map, numLocations, oneNorm, plusEqualsSparse, plusEqualsSparse, print, removeDuplicates, setAll, setValue, setValueAtLocation, singleIndex, singleSize, singleToIndices, singleValue, sortIndices, timesEquals, timesEqualsSparse, timesEqualsSparse, twoNorm, value, value, valueAtLocation, vectorAdd

Methods inherited from class java.lang.Object

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

Constructor Detail

Multinomial

protected Multinomial(double[] probabilities,
                      Alphabet dictionary,
                      int size,
                      boolean copy,
                      boolean checkSum)

Multinomial

public Multinomial(double[] probabilities,
                   Alphabet dictionary)

Multinomial

public Multinomial(double[] probabilities,
                   int size)

Multinomial

public Multinomial(double[] probabilities)

Method Detail

size

public int size()

probability

public double probability(int featureIndex)

probability

public double probability(Object key)

logProbability

public double logProbability(int featureIndex)

logProbability

public double logProbability(Object key)

getAlphabet

public Alphabet getAlphabet()

Overrides:

getAlphabet in class FeatureVector

addProbabilitiesTo

public void addProbabilitiesTo(double[] vector)

randomIndex

public int randomIndex(Random r)

randomObject

public Object randomObject(Random r)

randomFeatureSequence

public FeatureSequence randomFeatureSequence(Random r,
                                             int length)

randomFeatureVector

public FeatureVector randomFeatureVector(Random r,
                                         int size)