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https://issues.apache.org/jira/browse/SOLR-822?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12642188#action_12642188
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Walter Underwood commented on SOLR-822:
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Yes, it should be in Lucene. LIke this:
http://webui.sourcelabs.com/lucene/issues/1343
There are (at least) four kinds of character mapping:
Unicode normalization from decomposed to composed forms (always safe).
Unicode normalization from compatability forms to standard forms (may change
the look, like fullwidth to halfwidth Latin).
Language-specific normalization, like "oe" to "รถ" (German-only).
Mappings that improve search but are linguistically dodgy, like stripping
accents and mapping katakana to hirigana.
wunder
> CharFilter - normalize characters before tokenizer
> --------------------------------------------------
>
> Key: SOLR-822
> URL: https://issues.apache.org/jira/browse/SOLR-822
> Project: Solr
> Issue Type: New Feature
> Components: Analysis
> Reporter: Koji Sekiguchi
> Priority: Minor
> Attachments: character-normalization.JPG, sample_mapping_ja.txt,
> SOLR-822.patch, SOLR-822.patch
>
>
> A new plugin which can be placed in front of <tokenizer/>.
> {code:xml}
> <fieldType name="textCharNorm" class="solr.TextField"
> positionIncrementGap="100" >
> <analyzer>
> <charFilter class="solr.MappingCharFilterFactory"
> mapping="mapping_ja.txt" />
> <tokenizer class="solr.MappingCJKTokenizerFactory"/>
> <filter class="solr.StopFilterFactory" ignoreCase="true"
> words="stopwords.txt"/>
> <filter class="solr.LowerCaseFilterFactory"/>
> </analyzer>
> </fieldType>
> {code}
> <charFilter/> can be multiple (chained). I'll post a JPEG file to show
> character normalization sample soon.
> MOTIVATION:
> In Japan, there are two types of tokenizers -- N-gram (CJKTokenizer) and
> Morphological Analyzer.
> When we use morphological analyzer, because the analyzer uses Japanese
> dictionary to detect terms,
> we need to normalize characters before tokenization.
> I'll post a patch soon, too.
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