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Posted to dev@lucene.apache.org by "Steven Rowe (JIRA)" <ji...@apache.org> on 2008/09/17 22:33:44 UTC

[jira] Commented: (LUCENE-1390) add ISOLatinAccentFilter and deprecate ISOLatin1AccentFilter

    [ https://issues.apache.org/jira/browse/LUCENE-1390?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12631931#action_12631931 ] 

Steven Rowe commented on LUCENE-1390:
-------------------------------------

I think that at a minimum, the Latin Extended Additional block [U+1E00-U+1EFF] should be added, since it is included in Unicode v3.0 (the version of Unicode that Java 1.4.2 is conformant with), and it consists mainly of characters which have exact diacritic-stripped ASCII versions.  Wikipedia doesn't seem to have a page for this block, and I can't find a code chart PDF for Unicode v3.0 on unicode.org, so here's the PDF for Unicode v5.1 (the latest version):

http://www.unicode.org/charts/PDF/U1E00.pdf

Probably should check against the [Unicode 3.0 data file|http://www.unicode.org/Public/3.0-Update1/UnicodeData-3.0.1.txt] to make sure there haven't been any changes to this block between v3.0 and v5.1.0 - i.e., to make sure that the above-linked PDF is accurate for Unicode v3.0.

There is one more Latin block listed in the [Unicode 3.0 blocks data file|http://www.unicode.org/Public/3.0-Update/Blocks-3.txt]: [Latin Extended-B|http://en.wikipedia.org/wiki/Latin_Extended-B_unicode_block].  Since many of the characters in this block don't have exact diacritic-stripped ASCII versions, maybe it could be argued that they shouldn't be included in this filter.  A fair proportion of them (maybe 40%), however, do.


> add ISOLatinAccentFilter and deprecate ISOLatin1AccentFilter
> ------------------------------------------------------------
>
>                 Key: LUCENE-1390
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1390
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Analysis
>         Environment: any
>            Reporter: Andi Vajda
>         Attachments: ISOLatinAccentFilter.java
>
>
> The ISOLatin1AccentFilter is removing accents from accented characters in the ISO Latin 1 character set.
> It does what it does and there is no bug with it.
> It would be nicer, though, if there was a more comprehensive version of this code that included not just ISO-Latin-1 (ISO-8859-1) but the entire Latin 1 and Latin Extended A unicode blocks.
> See: http://en.wikipedia.org/wiki/Latin-1_Supplement_unicode_block
> See: http://en.wikipedia.org/wiki/Latin_Extended-A_unicode_block
> That way, all languages using roman characters are covered.
> A new class, ISOLatinAccentFilter is attached. It is intended to supercede ISOLatin1AccentFilter which should get deprecated.

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