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  Informs a feature generator that the context of the adaptive data (typically a document) is no longer valid.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