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https://issues.apache.org/jira/browse/OPENNLP-1261?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16851080#comment-16851080
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Tim Allison commented on OPENNLP-1261:
--------------------------------------
I'm attaching the results comparing the before and after. The type of noise is
"plus or minus" 1 character...so that noised text likely has something within
the same unicode block as the original text.
It looks like there is a trivial decline in accuracy on shorter texts. Search
for "Accuracy Across Languages -- Detector/Length/Noise" and then go to
OpenNLPLangDetector in both files.
This largely fixes the problems with lengthy text (100000), but there are still
some language-specific degradations when moving from, say 10k to 100k.
{noformat}
LANG: bul
OpenNLPLangDetector len=10000 noise=0
lang=bul detected=bul cnt=150 percent=100.00%
{noformat}
{noformat}
LANG: bul
OpenNLPLangDetector len=50000 noise=0
lang=bul detected=che cnt=73 percent=48.67%
OpenNLPLangDetector len=50000 noise=0
lang=bul detected=rus cnt=45 percent=30.00%
OpenNLPLangDetector len=50000 noise=0
lang=bul detected=bul cnt=32 percent=21.33%
{noformat}
{noformat}
LANG: bul
OpenNLPLangDetector len=100000 noise=0
lang=bul detected=mkd cnt=113 percent=75.33%
OpenNLPLangDetector len=100000 noise=0
lang=bul detected=bak cnt=37 percent=24.67%
{noformat}
> Language Detector fails to predict language on long input texts
> ---------------------------------------------------------------
>
> Key: OPENNLP-1261
> URL: https://issues.apache.org/jira/browse/OPENNLP-1261
> Project: OpenNLP
> Issue Type: Improvement
> Components: Language Detector
> Reporter: Joern Kottmann
> Assignee: Joern Kottmann
> Priority: Major
> Attachments: langid_plus_minus_rollups.zip
>
>
> If the input text is very long, e.g. 100k chars, then the lang detect
> component fails to detect the language correctly, even though the text is
> only written in one language.
> This issue was tracked down to the context generator, where the count of the
> ngrams are ignored.
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