Package org.apache.tika.langdetect.opennlp

Class OpenNLPDetector

java.lang.Object

org.apache.tika.language.detect.LanguageDetector

org.apache.tika.langdetect.opennlp.OpenNLPDetector

public class OpenNLPDetector
extends LanguageDetector

This is based on OpenNLP's language detector. However, we've built our own ProbingLanguageDetector and our own language models.

To build our model, we followed OpenNLP's lead by using the (Leipzig corpus) as gathered and preprocessed ( big-data corpus ). We removed azj, plt, sun and zsm because our models couldn't sufficiently well distinguish them from related languages. We removed cmn in favor of the finer-grained zho-trad and zho-simp.

We then added the following languages from cc-100: ben-rom (Bengali Romanized), ful, gla, gug, hau, hin-rom, ibo, ful, linm mya-zaw, nso, orm, quz, roh, srd, ssw, tam-rom, tel-rom, tsn, urd-rom, wol, yor.

We ran our own train/devtest/test code because OpenNLPs required more sentences/data than were available for some languages.

Please open an issue on our JIRA if we made mistakes and/or had misunderstandings in our design choices or if you need to have other languages added.

Citations for the cc-100 corpus:

Unsupervised Cross-lingual Representation Learning at Scale, Alexis Conneau, Kartikay Khandelwal, Naman Goyal, Vishrav Chaudhary, Guillaume Wenzek, Francisco Guzmán, Edouard Grave, Myle Ott, Luke Zettlemoyer, Veselin Stoyanov, Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics (ACL), p. 8440-8451, July 2020, pdf, bib.

CCNet: Extracting High Quality Monolingual Datasets from Web Crawl Data, Guillaume Wenzek, Marie-Anne Lachaux, Alexis Conneau, Vishrav Chaudhary, Francisco Guzmán, Armand Joulin, Edouard Grave, Proceedings of the 12th Language Resources and Evaluation Conference (LREC), p. 4003-4012, May 2020, pdf, bib.

Field Summary

Fields inherited from class org.apache.tika.language.detect.LanguageDetector

mixedLanguages, shortText

Constructor Summary

Constructors

Constructor	Description
OpenNLPDetector()

Method Summary

Modifier and Type	Method	Description
void	addText(char[] cbuf, int off, int len)	This will buffer up to setMaxLength(int) and then ignore the rest of the text.
List<LanguageResult>	detectAll()	Detect languages based on previously submitted text (via addText calls).
String[]	getSupportedLanguages()
boolean	hasModel(String language)	Provide information about whether a model exists for a specific language.
LanguageDetector	loadModels()	No-op.
LanguageDetector	loadModels(Set<String> languages)	NOT SUPPORTED.
void	reset()	Reset statistics about the current document being processed
void	setMaxLength(int maxLength)
LanguageDetector	setPriors(Map<String,Float> languageProbabilities)	NOT YET SUPPORTED.

Methods inherited from class org.apache.tika.language.detect.LanguageDetector

addText, detect, detect, detectAll, getDefaultLanguageDetector, getLanguageDetectors, getLanguageDetectors, hasEnoughText, isMixedLanguages, isShortText, setMixedLanguages, setShortText

Methods inherited from class java.lang.Object

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

Constructor Details

OpenNLPDetector

public OpenNLPDetector()

Method Details

loadModels

public LanguageDetector loadModels()
                            throws IOException

No-op. Models are loaded statically.

Specified by:

loadModels in class LanguageDetector

Returns:

Throws:

IOException

loadModels

public LanguageDetector loadModels(Set<String> languages)
                            throws IOException

NOT SUPPORTED. Throws UnsupportedOperationException

Specified by:

loadModels in class LanguageDetector

Parameters:

languages - list of target languages.

Returns:

Throws:

IOException

hasModel

public boolean hasModel(String language)

Description copied from class: LanguageDetector

Provide information about whether a model exists for a specific language.

Specified by:

hasModel in class LanguageDetector

Parameters:

language - ISO 639-1 name for language

Returns:

true if a model for this language exists.

setPriors

public LanguageDetector setPriors(Map<String,Float> languageProbabilities)
                           throws IOException

NOT YET SUPPORTED. Throws UnsupportedOperationException

Specified by:

setPriors in class LanguageDetector

Parameters:

languageProbabilities - Map from language to probability

Returns:

Throws:

IOException

reset

public void reset()

Description copied from class: LanguageDetector

Reset statistics about the current document being processed

Specified by:

reset in class LanguageDetector

addText

public void addText(char[] cbuf,
 int off,
 int len)

This will buffer up to setMaxLength(int) and then ignore the rest of the text.

Specified by:

addText in class LanguageDetector

Parameters:

cbuf - Character buffer

off - Offset into cbuf to first character in the run of text

len - Number of characters in the run of text.

detectAll

public List<LanguageResult> detectAll()

Description copied from class: LanguageDetector

Detect languages based on previously submitted text (via addText calls).

Specified by:

detectAll in class LanguageDetector

Returns:

list of all possible languages with at least medium confidence, sorted by confidence from highest to lowest. There will always be at least one result, which might have a confidence of NONE.

setMaxLength

public void setMaxLength(int maxLength)

getSupportedLanguages

public String[] getSupportedLanguages()