Package opennlp.tools.util.featuregen

Class WindowFeatureGenerator

java.lang.Object

opennlp.tools.util.featuregen.WindowFeatureGenerator

All Implemented Interfaces:

AdaptiveFeatureGenerator

public class WindowFeatureGenerator
extends Object
implements AdaptiveFeatureGenerator

Generates previous (left-sided) and next (right-sided) features for a given AdaptiveFeatureGenerator. The window size can be specified.

Features:

• Current token is always included unchanged,
• Previous tokens are prefixed with p distance,
• Next tokens are prefix with n distance.

See Also:

• AdaptiveFeatureGenerator

Field Summary

Fields

Modifier and Type	Field	Description
static final String	NEXT_PREFIX
static final String	PREV_PREFIX

Constructor Summary

Constructors

Constructor	Description
WindowFeatureGenerator(int prevWindowSize, int nextWindowSize, AdaptiveFeatureGenerator... generators)	Initializes a WindowFeatureGenerator with the given parameters.
WindowFeatureGenerator(AdaptiveFeatureGenerator generator)	Initializes a WindowFeatureGenerator.
WindowFeatureGenerator(AdaptiveFeatureGenerator... generators)	Initializes a WindowFeatureGenerator.
WindowFeatureGenerator(AdaptiveFeatureGenerator generator, int prevWindowSize, int nextWindowSize)	Initializes a WindowFeatureGenerator with the given parameters.

Method Summary

Modifier and Type	Method	Description
void	clearAdaptiveData()	Informs a feature generator that the context of the adaptive data (typically a document) is no longer valid.
void	createFeatures(List<String> features, String[] tokens, int index, String[] preds)	Adds the appropriate features for the token at the specified index with the specified array of previousOutcomes to the specified list of features.
String	toString()
void	updateAdaptiveData(String[] tokens, String[] outcomes)	Informs a feature generator that the specified tokens have been classified with the corresponding set of specified outcomes.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

PREV_PREFIX

public static final String PREV_PREFIX

See Also:

• Constant Field Values

NEXT_PREFIX

public static final String NEXT_PREFIX

See Also:

• Constant Field Values

Constructor Details

WindowFeatureGenerator

public WindowFeatureGenerator(AdaptiveFeatureGenerator generator,
 int prevWindowSize,
 int nextWindowSize)

Initializes a WindowFeatureGenerator with the given parameters.

Parameters:

generator - The AdaptiveFeatureGenerator to apply to the window.

prevWindowSize - Size of the window to the left of the current token.

nextWindowSize - Size of the window to the right of the current token.

WindowFeatureGenerator

public WindowFeatureGenerator(int prevWindowSize,
 int nextWindowSize,
 AdaptiveFeatureGenerator... generators)

Initializes a WindowFeatureGenerator with the given parameters.

Parameters:

generators - One or more AdaptiveFeatureGenerator to apply to the window.

prevWindowSize - Size of the window to the left of the current token.

nextWindowSize - Size of the window to the right of the current token.

WindowFeatureGenerator

public WindowFeatureGenerator(AdaptiveFeatureGenerator generator)

Initializes a WindowFeatureGenerator. The previous and next window size is 5.

Parameters:

generator - The AdaptiveFeatureGenerator to apply to the window.

WindowFeatureGenerator

public WindowFeatureGenerator(AdaptiveFeatureGenerator... generators)

Initializes a WindowFeatureGenerator. The previous and next window size is 5.

Parameters:

generators - One or more AdaptiveFeatureGenerator to apply to the window.

Method Details

createFeatures

public void createFeatures(List<String> features,
 String[] tokens,
 int index,
 String[] preds)

Description copied from interface: AdaptiveFeatureGenerator

Adds the appropriate features for the token at the specified index with the specified array of previousOutcomes to the specified list of features.

Specified by:

createFeatures in interface AdaptiveFeatureGenerator

Parameters:

features - The list of features to be added to.

tokens - The tokens of the sentence or other text unit being processed.

index - The index of the token which is currently being processed.

preds - The outcomes for the tokens prior to the specified index.

updateAdaptiveData

public void updateAdaptiveData(String[] tokens,
 String[] outcomes)

Description copied from interface: AdaptiveFeatureGenerator

Informs a feature generator that the specified tokens have been classified with the corresponding set of specified outcomes.

Specified by:

updateAdaptiveData in interface AdaptiveFeatureGenerator

Parameters:

tokens - The tokens of the sentence or other text unit which has been processed.

outcomes - The outcomes associated with the specified tokens.

clearAdaptiveData

public void clearAdaptiveData()

Description copied from interface: AdaptiveFeatureGenerator

Informs a feature generator that the context of the adaptive data (typically a document) is no longer valid.

Specified by:

clearAdaptiveData in interface AdaptiveFeatureGenerator

toString

public String toString()

Overrides:

toString in class Object