Class JapaneseTokenizer

Tokenizer for Japanese that uses morphological analysis.

Inheritance

object

AttributeSource

TokenStream

Tokenizer

JapaneseTokenizer

Implements

IDisposable

Inherited Members

Tokenizer.SetReader(TextReader)

TokenStream.Dispose()

AttributeSource.GetAttributeFactory()

AttributeSource.GetAttributeClassesEnumerator()

AttributeSource.GetAttributeImplsEnumerator()

AttributeSource.AddAttributeImpl(Attribute)

AttributeSource.AddAttribute<T>()

AttributeSource.HasAttributes

AttributeSource.HasAttribute<T>()

AttributeSource.GetAttribute<T>()

AttributeSource.ClearAttributes()

AttributeSource.CaptureState()

AttributeSource.RestoreState(AttributeSource.State)

AttributeSource.GetHashCode()

AttributeSource.Equals(object)

AttributeSource.ReflectAsString(bool)

AttributeSource.ReflectWith(IAttributeReflector)

AttributeSource.CloneAttributes()

AttributeSource.CopyTo(AttributeSource)

AttributeSource.ToString()

object.Equals(object, object)

object.GetType()

object.ReferenceEquals(object, object)

Namespace: Lucene.Net.Analysis.Ja

Assembly: Lucene.Net.Analysis.Kuromoji.dll

Syntax

public sealed class JapaneseTokenizer : Tokenizer, IDisposable

Remarks

This tokenizer sets a number of additional attributes:

• IBaseFormAttribute containing base form for inflected adjectives and verbs.
• IPartOfSpeechAttribute containing part-of-speech.
• IReadingAttribute containing reading and pronunciation.
• IInflectionAttribute containing additional part-of-speech information for inflected forms.

This tokenizer uses a rolling Viterbi search to find the least cost segmentation (path) of the incoming characters. For tokens that appear to be compound (> length 2 for all Kanji, or > length 7 for non-Kanji), we see if there is a 2nd best segmentation of that token after applying penalties to the long tokens. If so, and the Mode is SEARCH, we output the alternate segmentation as well.

Constructors

JapaneseTokenizer(AttributeFactory, TextReader, UserDictionary, bool, JapaneseTokenizerMode)

Create a new JapaneseTokenizer.

Declaration

public JapaneseTokenizer(AttributeSource.AttributeFactory factory, TextReader input, UserDictionary userDictionary, bool discardPunctuation, JapaneseTokenizerMode mode)

Parameters

Type	Name	Description
AttributeSource.AttributeFactory	factory	The AttributeFactory to use.
TextReader	input	TextReader containing text.
UserDictionary	userDictionary	Optional: if non-null, user dictionary.
bool	discardPunctuation	true if punctuation tokens should be dropped from the output.
JapaneseTokenizerMode	mode	Tokenization mode.

Remarks

This tokenizer sets a number of additional attributes:

• IBaseFormAttribute containing base form for inflected adjectives and verbs.
• IPartOfSpeechAttribute containing part-of-speech.
• IReadingAttribute containing reading and pronunciation.
• IInflectionAttribute containing additional part-of-speech information for inflected forms.

This tokenizer uses a rolling Viterbi search to find the least cost segmentation (path) of the incoming characters. For tokens that appear to be compound (> length 2 for all Kanji, or > length 7 for non-Kanji), we see if there is a 2nd best segmentation of that token after applying penalties to the long tokens. If so, and the Mode is SEARCH, we output the alternate segmentation as well.

JapaneseTokenizer(TextReader, UserDictionary, bool, JapaneseTokenizerMode)

Create a new JapaneseTokenizer.

Uses the default AttributeFactory.

Declaration

public JapaneseTokenizer(TextReader input, UserDictionary userDictionary, bool discardPunctuation, JapaneseTokenizerMode mode)

Parameters

Type	Name	Description
TextReader	input	TextReader containing text.
UserDictionary	userDictionary	Optional: if non-null, user dictionary.
bool	discardPunctuation	true if punctuation tokens should be dropped from the output.
JapaneseTokenizerMode	mode	Tokenization mode.

Remarks

This tokenizer sets a number of additional attributes:

• IBaseFormAttribute containing base form for inflected adjectives and verbs.
• IPartOfSpeechAttribute containing part-of-speech.
• IReadingAttribute containing reading and pronunciation.
• IInflectionAttribute containing additional part-of-speech information for inflected forms.

This tokenizer uses a rolling Viterbi search to find the least cost segmentation (path) of the incoming characters. For tokens that appear to be compound (> length 2 for all Kanji, or > length 7 for non-Kanji), we see if there is a 2nd best segmentation of that token after applying penalties to the long tokens. If so, and the Mode is SEARCH, we output the alternate segmentation as well.

Fields

DEFAULT_MODE

Default tokenization mode. Currently this is SEARCH.

Declaration

public static readonly JapaneseTokenizerMode DEFAULT_MODE

Field Value

Type	Description
JapaneseTokenizerMode

Remarks

This tokenizer sets a number of additional attributes:

• IBaseFormAttribute containing base form for inflected adjectives and verbs.
• IPartOfSpeechAttribute containing part-of-speech.
• IReadingAttribute containing reading and pronunciation.
• IInflectionAttribute containing additional part-of-speech information for inflected forms.

This tokenizer uses a rolling Viterbi search to find the least cost segmentation (path) of the incoming characters. For tokens that appear to be compound (> length 2 for all Kanji, or > length 7 for non-Kanji), we see if there is a 2nd best segmentation of that token after applying penalties to the long tokens. If so, and the Mode is SEARCH, we output the alternate segmentation as well.

Properties

GraphvizFormatter

Expert: set this to produce graphviz (dot) output of the Viterbi lattice

Declaration

public GraphvizFormatter GraphvizFormatter { get; set; }

Property Value

Type	Description
GraphvizFormatter

Remarks

This tokenizer sets a number of additional attributes:

• IBaseFormAttribute containing base form for inflected adjectives and verbs.
• IPartOfSpeechAttribute containing part-of-speech.
• IReadingAttribute containing reading and pronunciation.
• IInflectionAttribute containing additional part-of-speech information for inflected forms.

This tokenizer uses a rolling Viterbi search to find the least cost segmentation (path) of the incoming characters. For tokens that appear to be compound (> length 2 for all Kanji, or > length 7 for non-Kanji), we see if there is a 2nd best segmentation of that token after applying penalties to the long tokens. If so, and the Mode is SEARCH, we output the alternate segmentation as well.

Methods

Dispose(bool)

Releases resources associated with this stream.

If you override this method, always call base.Dispose(disposing), otherwise some internal state will not be correctly reset (e.g., Lucene.Net.Analysis.Tokenizer will throw InvalidOperationException on reuse).

Declaration

protected override void Dispose(bool disposing)

Parameters

Type	Name	Description
bool	disposing

Overrides

Tokenizer.Dispose(bool)

Remarks

NOTE: The default implementation closes the input TextReader, so be sure to call base.Dispose(disposing) when overriding this method.

End()

This method is called by the consumer after the last token has been consumed, after Lucene.Net.Analysis.TokenStream.IncrementToken() returned false (using the new Lucene.Net.Analysis.TokenStream API). Streams implementing the old API should upgrade to use this feature.

This method can be used to perform any end-of-stream operations, such as setting the final offset of a stream. The final offset of a stream might differ from the offset of the last token eg in case one or more whitespaces followed after the last token, but a WhitespaceTokenizer was used.

Additionally any skipped positions (such as those removed by a stopfilter) can be applied to the position increment, or any adjustment of other attributes where the end-of-stream value may be important.

If you override this method, always call base.End();.

Declaration

public override void End()

Overrides

Lucene.Net.Analysis.TokenStream.End()

Remarks

This tokenizer sets a number of additional attributes:

• IBaseFormAttribute containing base form for inflected adjectives and verbs.
• IPartOfSpeechAttribute containing part-of-speech.
• IReadingAttribute containing reading and pronunciation.
• IInflectionAttribute containing additional part-of-speech information for inflected forms.

This tokenizer uses a rolling Viterbi search to find the least cost segmentation (path) of the incoming characters. For tokens that appear to be compound (> length 2 for all Kanji, or > length 7 for non-Kanji), we see if there is a 2nd best segmentation of that token after applying penalties to the long tokens. If so, and the Mode is SEARCH, we output the alternate segmentation as well.

Exceptions

Type	Condition
IOException	If an I/O error occurs

IncrementToken()

Consumers (i.e., Lucene.Net.Index.IndexWriter) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate Lucene.Net.Util.IAttributes with the attributes of the next token.

The producer must make no assumptions about the attributes after the method has been returned: the caller may arbitrarily change it. If the producer needs to preserve the state for subsequent calls, it can use Lucene.Net.Util.AttributeSource.CaptureState() to create a copy of the current attribute state.

this method is called for every token of a document, so an efficient implementation is crucial for good performance. To avoid calls to Lucene.Net.Util.AttributeSource.AddAttribute<T>() and Lucene.Net.Util.AttributeSource.GetAttribute<T>(), references to all Lucene.Net.Util.IAttributes that this stream uses should be retrieved during instantiation.

To ensure that filters and consumers know which attributes are available, the attributes must be added during instantiation. Filters and consumers are not required to check for availability of attributes in Lucene.Net.Analysis.TokenStream.IncrementToken().

Declaration

public override bool IncrementToken()

Returns

Type	Description
bool	false for end of stream; true otherwise

Overrides

Lucene.Net.Analysis.TokenStream.IncrementToken()

Remarks

This tokenizer sets a number of additional attributes:

• IBaseFormAttribute containing base form for inflected adjectives and verbs.
• IPartOfSpeechAttribute containing part-of-speech.
• IReadingAttribute containing reading and pronunciation.
• IInflectionAttribute containing additional part-of-speech information for inflected forms.

This tokenizer uses a rolling Viterbi search to find the least cost segmentation (path) of the incoming characters. For tokens that appear to be compound (> length 2 for all Kanji, or > length 7 for non-Kanji), we see if there is a 2nd best segmentation of that token after applying penalties to the long tokens. If so, and the Mode is SEARCH, we output the alternate segmentation as well.

Reset()

This method is called by a consumer before it begins consumption using Lucene.Net.Analysis.TokenStream.IncrementToken().

Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.

If you override this method, always call base.Reset(), otherwise some internal state will not be correctly reset (e.g., Lucene.Net.Analysis.Tokenizer will throw InvalidOperationException on further usage).

Declaration

public override void Reset()

Overrides

Lucene.Net.Analysis.Tokenizer.Reset()

Remarks

This tokenizer sets a number of additional attributes:

• IBaseFormAttribute containing base form for inflected adjectives and verbs.
• IPartOfSpeechAttribute containing part-of-speech.
• IReadingAttribute containing reading and pronunciation.
• IInflectionAttribute containing additional part-of-speech information for inflected forms.

This tokenizer uses a rolling Viterbi search to find the least cost segmentation (path) of the incoming characters. For tokens that appear to be compound (> length 2 for all Kanji, or > length 7 for non-Kanji), we see if there is a 2nd best segmentation of that token after applying penalties to the long tokens. If so, and the Mode is SEARCH, we output the alternate segmentation as well.

Implements

IDisposable