Class StemmerAnnotator

java.lang.Object

opennlp.tools.stemmer.StemmerAnnotator

All Implemented Interfaces:

opennlp.tools.document.DocumentAnnotator

public final class StemmerAnnotator
extends Object
implements opennlp.tools.document.DocumentAnnotator

Adapts a Stemmer to the document pipeline: stems the token layer and provides STEMS, one annotation per token on the token's span.

Stemming operates on the token surface alone, so this annotator requires only the token layer; no part-of-speech tags are involved.

Since:

3.0.0

Field Summary

Fields

Modifier and Type	Field	Description
static final opennlp.tools.document.LayerKey<String>	STEMS	The stem layer.

Constructor Summary

Constructors

Constructor	Description
StemmerAnnotator(opennlp.tools.stemmer.Stemmer stemmer)	Initializes the adapter.

Method Summary

Modifier and Type	Method	Description
opennlp.tools.document.Document	annotate(opennlp.tools.document.Document document)	Stems the token layer and adds the STEMS layer.
Set<opennlp.tools.document.LayerKey<?>>	provides()
Set<opennlp.tools.document.LayerKey<?>>	requires()
String	toString()	Returns the adapter's simple class name, which names it in pipeline validation messages.

Methods inherited from class Object

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

Field Details

STEMS

public static final opennlp.tools.document.LayerKey<String> STEMS

The stem layer. It is aligned with the token layer by position, and each annotation carries the stem of its token on that token's span.

Constructor Details

StemmerAnnotator

public StemmerAnnotator(opennlp.tools.stemmer.Stemmer stemmer)

Initializes the adapter.

Parameters:

stemmer - The stemmer to delegate to. Must not be null.

Throws:

IllegalArgumentException - Thrown if stemmer is null.

Method Details

annotate

public opennlp.tools.document.Document annotate(opennlp.tools.document.Document document)

Stems the token layer and adds the STEMS layer.

The token layer must be present, but it may be empty: a document without tokens yields a present-but-empty stem layer.

Specified by:

annotate in interface opennlp.tools.document.DocumentAnnotator

Parameters:

document - The document to annotate. Must not be null and must carry the Layers.TOKENS layer.

Returns:

A new Document with the STEMS layer added. Never null.

Throws:

IllegalArgumentException - Thrown if document is null or the token layer is absent.

requires

public Set<opennlp.tools.document.LayerKey<?>> requires()

Specified by:

requires in interface opennlp.tools.document.DocumentAnnotator

provides

public Set<opennlp.tools.document.LayerKey<?>> provides()

Specified by:

provides in interface opennlp.tools.document.DocumentAnnotator

toString

public String toString()

Returns the adapter's simple class name, which names it in pipeline validation messages.

Overrides:

toString in class Object

Returns:

the adapter's simple class name, which names it in pipeline validation messages