cc.mallet.types
Class FeatureSequence

java.lang.Object
  cc.mallet.types.FeatureSequence

All Implemented Interfaces:

AlphabetCarrying, Sequence, java.io.Serializable

Direct Known Subclasses:

FeatureSequenceWithBigrams, LabelSequence

public class FeatureSequence
extends java.lang.Object
implements Sequence, java.io.Serializable, AlphabetCarrying

An implementation of Sequence that ensures that every Object in the sequence has the same class. Feature sequences are mutable, and will expand as new objects are added.

Author:

Andrew McCallum mccallum@cs.umass.edu

See Also:

Serialized Form

Constructor Summary

FeatureSequence(Alphabet dict)

FeatureSequence(Alphabet dict, int capacity)

FeatureSequence(Alphabet dict, int[] features)
Creates a FeatureSequence given all of the objects in the sequence.

FeatureSequence(Alphabet dict, int[] features, int len)

Method Summary

void	add(int featureIndex)
void	add(java.lang.Object key)
void	addFeatureWeightsTo(double[] weights)
void	addFeatureWeightsTo(double[] weights, double scale)
boolean	alphabetsMatch(AlphabetCarrying object)
java.lang.Object	get(int pos)
Alphabet	getAlphabet()
Alphabet[]	getAlphabets()
int[]	getFeatures()
int	getIndexAtPosition(int pos)
int	getLength()
java.lang.Object	getObjectAtPosition(int pos)
protected void	growIfNecessary()
void	prune(double[] counts, Alphabet newAlphabet, int cutoff) Remove features from the sequence that occur fewer than cutoff times in the corpus, as indicated by the provided counts.
int	size()
int[]	toFeatureIndexSequence()
int[]	toSortedFeatureIndexSequence()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

FeatureSequence

public FeatureSequence(Alphabet dict,
                       int[] features)

Creates a FeatureSequence given all of the objects in the sequence.

Parameters:

dict - A dictionary that maps objects in the sequence to numeric indices.

features - An array where features[i] gives the index in dict of the ith element of the sequence.

FeatureSequence

public FeatureSequence(Alphabet dict,
                       int[] features,
                       int len)

FeatureSequence

public FeatureSequence(Alphabet dict,
                       int capacity)

FeatureSequence

public FeatureSequence(Alphabet dict)

Method Detail

getFeatures

public int[] getFeatures()

getAlphabet

public Alphabet getAlphabet()

Specified by:

getAlphabet in interface AlphabetCarrying

getAlphabets

public Alphabet[] getAlphabets()

Specified by:

getAlphabets in interface AlphabetCarrying

alphabetsMatch

public boolean alphabetsMatch(AlphabetCarrying object)

getLength

public final int getLength()

size

public final int size()

Specified by:

size in interface Sequence

getIndexAtPosition

public final int getIndexAtPosition(int pos)

getObjectAtPosition

public java.lang.Object getObjectAtPosition(int pos)

get

public java.lang.Object get(int pos)

Specified by:

get in interface Sequence

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

growIfNecessary

protected void growIfNecessary()

add

public void add(int featureIndex)

add

public void add(java.lang.Object key)

addFeatureWeightsTo

public void addFeatureWeightsTo(double[] weights)

addFeatureWeightsTo

public void addFeatureWeightsTo(double[] weights,
                                double scale)

toFeatureIndexSequence

public int[] toFeatureIndexSequence()

toSortedFeatureIndexSequence

public int[] toSortedFeatureIndexSequence()

prune

public void prune(double[] counts,
                  Alphabet newAlphabet,
                  int cutoff)

Remove features from the sequence that occur fewer than cutoff times in the corpus, as indicated by the provided counts. Also swap in the new, reduced alphabet. This method alters the instance in place; it is not appropriate if the original instance will be needed.