Lingua::Stem::Snowball - Perl interface to Snowball stemmers.

       Lingua::Stem::Snowball  was originally developed to provide access to stemming algorithms for the OpenFTS
       (full text search engine) project (<http://openfts.sourceforge.net>), by Oleg Bartunov, <oleg at sai  dot
       msu dot su> and Teodor Sigaev, <teodor at stack dot net>.

       Currently maintained by Marvin Humphrey <marvin at rectangular dot com>.  Previously maintained by Fabien
       Potencier <fabpot at cpan dot org>.

       Perl bindings copyright 2004-2008 by Marvin Humphrey, Fabien Potencier, Oleg Bartunov and Teodor Sigaev.

       This software may be freely copied and distributed under the same terms and conditions as Perl.

       Snowball files and stemmers are covered by the BSD license.

       Stemming reduces related words to a common root form -- for instance, "horse", "horses", and "horsing"
       all become "hors".  Most commonly, stemming is deployed as part of a search application, allowing
       searches for a given term to match documents which contain other forms of that term.

       This module is very similar to Lingua::Stem -- however, Lingua::Stem is pure Perl, while
       Lingua::Stem::Snowball is an XS module which provides a Perl interface to the C version of the Snowball
       stemmers.  (<http://snowball.tartarus.org>).

   SupportedLanguages
       The following stemmers are available (as of Lingua::Stem::Snowball 0.95):

           |-----------------------------------------------------------|
           | Language   | ISO code | default encoding | also available |
           |-----------------------------------------------------------|
           | Danish     | da       | ISO-8859-1       | UTF-8          |
           | Dutch      | nl       | ISO-8859-1       | UTF-8          |
           | English    | en       | ISO-8859-1       | UTF-8          |
           | Finnish    | fi       | ISO-8859-1       | UTF-8          |
           | French     | fr       | ISO-8859-1       | UTF-8          |
           | German     | de       | ISO-8859-1       | UTF-8          |
           | Hungarian  | hu       | ISO-8859-1       | UTF-8          |
           | Italian    | it       | ISO-8859-1       | UTF-8          |
           | Norwegian  | no       | ISO-8859-1       | UTF-8          |
           | Portuguese | pt       | ISO-8859-1       | UTF-8          |
           | Romanian   | ro       | ISO-8859-2       | UTF-8          |
           | Russian    | ru       | KOI8-R           | UTF-8          |
           | Spanish    | es       | ISO-8859-1       | UTF-8          |
           | Swedish    | sv       | ISO-8859-1       | UTF-8          |
           | Turkish    | tr       | UTF-8            |                |
           |-----------------------------------------------------------|

   Benchmarks
       Here is a comparison of Lingua::Stem::Snowball and Lingua::Stem, using The Works of Edgar Allen Poe,
       volumes 1-5 (via Project Gutenberg) as source material.  It was produced on a 3.2GHz Pentium 4 running
       FreeBSD 5.3 and Perl 5.8.7.  (The benchmarking script is included in this distribution:
       devel/benchmark_stemmers.plx.)

           |--------------------------------------------------------------------|
           | total words: 454285 | unique words: 22748                          |
           |--------------------------------------------------------------------|
           | module                        | config        | avg secs | rate    |
           |--------------------------------------------------------------------|
           | Lingua::Stem 0.81             | no cache      | 2.029    | 223881  |
           | Lingua::Stem 0.81             | cache level 2 | 1.280    | 355025  |
           | Lingua::Stem::Snowball 0.94   | stem          | 1.426    | 318636  |
           | Lingua::Stem::Snowball 0.94   | stem_in_place | 0.641    | 708495  |
           |--------------------------------------------------------------------|

new
           my $stemmer = Lingua::Stem::Snowball->new(
               lang     => 'es',
               encoding => 'UTF-8',
           );
           die $@ if $@;

       Create a Lingua::Stem::Snowball object.  new() accepts the following hash style parameters:

       •   lang: An ISO code taken from the table of supported languages, above.

       •   encoding: A supported character encoding.

       Be  careful  with  the  values you supply to new(). If "lang" is invalid, Lingua::Stem::Snowball does not
       throw an exception, but instead sets $@.  Also, if you supply an invalid combination of values for "lang"
       and "encoding", Lingua::Stem::Snowball will not warn you, but  the  behavior  will  change:  stem()  will
       always return undef, and stem_in_place() will be a no-op.

   stem
           @stemmed = $stemmer->stem( WORDS, [IS_STEMMED] );
           @stemmed = stem( ISO_CODE, WORDS, [LOCALE], [IS_STEMMED] );

       Return lowercased and stemmed output.  WORDS may be either an array of words or a single scalar word.

       In a scalar context, stem() returns the first item in the array of stems:

           $stem       = $stemmer->stem($word);
           $first_stem = $stemmer->stem(\@words); # probably wrong

       LOCALE  has  no  effect;  it  is  only  there as a placeholder for backwards compatibility (see Changes).
       IS_STEMMED must be a reference to a scalar; if it is supplied, it will be set to 1 if the output  differs
       from the input in some way, 0 otherwise.

   stem_in_place
           $stemmer->stem_in_place(\@words);

       This  is  a  high-performance,  streamlined  version  of  stem()  (in  fact, stem() calls stem_in_place()
       internally). It has no return value, instead modifying each item in an  existing  array  of  words.   The
       words must already be in lower case.

   lang
           my $lang = $stemmer->lang;
           $stemmer->lang($iso_language_code);

       Accessor/mutator  for  the lang parameter. If there is no stemmer for the supplied ISO code, the language
       is not changed (but $@ is set).

   encoding
           my $encoding = $stemmer->encoding;
           $stemmer->encoding($encoding);

       Accessor/mutator for the encoding parameter.

   stemmers
           my @iso_codes = stemmers();
           my @iso_codes = $stemmer->stemmers();

       Returns a list of all valid language codes.

       Lingua::Stem::Snowball - Perl interface to Snowball stemmers.

       Please report any requests, suggestions or bugs via the RT bug-tracking system at http://rt.cpan.org/  or
       email to bug-Lingua-Stem-Snowball@rt.cpan.org.

       http://rt.cpan.org/NoAuth/Bugs.html?Dist=Lingua-Stem-Snowball is the RT queue for Lingua::Stem::Snowball.
       Please check to see if your bug has already been reported.

       <http://snowball.tartarus.org>, Lingua::Stem.

perl v5.40.0                                       2024-10-20                        Lingua::Stem::Snowball(3pm)

           my @words = qw( horse hooves );

           # OO interface:
           my $stemmer = Lingua::Stem::Snowball->new( lang => 'en' );
           $stemmer->stem_in_place( \@words ); # qw( hors hoov )

           # Functional interface:
           my @stems = stem( 'en', \@words );