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From "Robert Muir (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-4345) Create a Classification module
Date Sat, 15 Sep 2012 14:14:07 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-4345?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13456415#comment-13456415
] 

Robert Muir commented on LUCENE-4345:
-------------------------------------

I don't think this should be using payloads to pull POS tags: the purpose of payloads
is when you need something stored in the actual index (and should be limited to e.g. a single
byte),
its not type-safe but application-specific.

Instead such taggers should expose a type-safe PartOfSpeechAttribute as suggested in the
o.a.l.analysis package javadocs. If they want to put POS into the index for e.g. payload-based
queries,
thats a separate concern, they should have a separate tokenfilter that encodes the POS attribute
into the payload so this is optional (as it has tradeoffs in the index). See TypeAsPayloadFilter
etc
as an example of what I mean. But for this module we don't need anything in the index.

If we think its useful for classifiers to limit the analysis to certain POS categories, then
instead we should factor out a *minimal* POSAttribute sub-interface with something very generic
like isNominal()/isVerbal() that can actually be implemented by different taggers with different
tag sets
across different languages.

Then things like kuromoji's POSAttribute, openNLP's POSAttribute, or even your custom home-grown
one,
or some commercial one could extend this sub-interface and plug into it.

At least i think this is possible with our attributes API :)

                
> Create a Classification module
> ------------------------------
>
>                 Key: LUCENE-4345
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4345
>             Project: Lucene - Core
>          Issue Type: New Feature
>            Reporter: Tommaso Teofili
>            Assignee: Tommaso Teofili
>            Priority: Minor
>         Attachments: LUCENE-4345_2.patch, LUCENE-4345.patch, SOLR-3700_2.patch, SOLR-3700.patch
>
>
> Lucene/Solr can host huge sets of documents containing lots of information in fields
so that these can be used as training examples (w/ features) in order to very quickly create
classifiers algorithms to use on new documents and / or to provide an additional service.
> So the idea is to create a contrib module (called 'classification') to host a ClassificationComponent
that will use already seen data (the indexed documents / fields) to classify new documents
/ text fragments.
> The first version will contain a (simplistic) Lucene based Naive Bayes classifier but
more implementations should be added in the future.

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