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https://issues.apache.org/jira/browse/LUCENE-5558?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13951154#comment-13951154
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Robert Muir commented on LUCENE-5558:
-------------------------------------
I think we should add validation for these filters!
As far as TestRandomChains detecting an empty token stream, this is ok. it
generates random data and the chain may correctly remove all the tokens.
> Add TruncateTokenFilter
> -----------------------
>
> Key: LUCENE-5558
> URL: https://issues.apache.org/jira/browse/LUCENE-5558
> Project: Lucene - Core
> Issue Type: New Feature
> Components: modules/analysis
> Affects Versions: 4.7
> Reporter: Ahmet Arslan
> Priority: Minor
> Labels: Turkish, f5
> Fix For: 4.8
>
> Attachments: LUCENE-5558.patch, LUCENE-5558.patch, LUCENE-5558.patch
>
>
> I am using this filter as a stemmer for Turkish language. In many academic
> research (classification, retrieval) it is used and called as Fixed Prefix
> Stemmer or Simple Truncation Method or F5 in short.
> Among F3 TO F7, F5 stemmer (length=5) is found to work well for Turkish
> language in [Information Retrieval on Turkish
> Texts|http://www.users.muohio.edu/canf/papers/JASIST2008offPrint.pdf]. It is
> the same work where most of stopwords_tr.txt are acquired.
> ElasticSearch has
> [truncate|http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/analysis-truncate-tokenfilter.html]
> filter but it does not respect keyword attribute. And it has a use case
> similar to TruncateFieldUpdateProcessorFactory
> Main advantage of F5 stemming is : it does not effected by the meaning loss
> caused by ascii folding. It is a diacritics-insensitive stemmer and works
> well with ascii folding. [Effects of diacritics on Turkish information
> retrieval|http://journals.tubitak.gov.tr/elektrik/issues/elk-12-20-5/elk-20-5-9-1010-819.pdf]
> Here is the full field type I use for "diacritics-insensitive search" for
> Turkish
> {code:xml}
> <fieldType name="text_tr_ascii_f5" class="solr.TextField"
> positionIncrementGap="100">
> <analyzer>
> <tokenizer class="solr.StandardTokenizerFactory"/>
> <filter class="solr.ApostropheFilterFactory"/>
> <filter class="solr.TurkishLowerCaseFilterFactory"/>
> <filter class="solr.ASCIIFoldingFilterFactory"/>
> <filter class="solr.KeywordRepeatFilterFactory"/>
> <filter class="solr.TruncateTokenFilterFactory" prefixLength="5"/>
> <filter class="solr.RemoveDuplicatesTokenFilterFactory"/>
> </analyzer>
> {code}
> I would like to get community opinions :
> 1) Any interest in this?
> 2) keyword attribute should be respected?
> 3) package name analysis.misc versus analyis.tr
> 4) name of the class TruncateTokenFilter versus FixedPrefixStemFilter
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