https://github.com/patch/lingua-stem-any-pm5
Lingua::Stem::Any (Perl 5): Unified interface to any stemmer on CPAN (Perl 5)
https://github.com/patch/lingua-stem-any-pm5
Last synced: 10 months ago
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Lingua::Stem::Any (Perl 5): Unified interface to any stemmer on CPAN (Perl 5)
- Host: GitHub
- URL: https://github.com/patch/lingua-stem-any-pm5
- Owner: patch
- License: other
- Created: 2013-03-27T15:52:57.000Z (almost 13 years ago)
- Default Branch: master
- Last Pushed: 2014-08-29T06:24:52.000Z (over 11 years ago)
- Last Synced: 2025-02-03T08:48:05.562Z (12 months ago)
- Language: Perl
- Homepage: https://metacpan.org/pod/Lingua::Stem::Any
- Size: 438 KB
- Stars: 4
- Watchers: 3
- Forks: 0
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- Changelog: Changes
- License: LICENSE
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# NAME
Lingua::Stem::Any - Unified interface to any stemmer on CPAN
# VERSION
This document describes Lingua::Stem::Any v0.05.
# SYNOPSIS
```perl
use Lingua::Stem::Any;
# create German stemmer using the default source module
$stemmer = Lingua::Stem::Any->new(language => 'de');
# create German stemmer explicitly using Lingua::Stem::Snowball
$stemmer = Lingua::Stem::Any->new(
language => 'de',
source => 'Lingua::Stem::Snowball',
);
# get stem for word
$stem = $stemmer->stem($word);
# get list of stems for list of words
@stems = $stemmer->stem(@words);
```
# DESCRIPTION
This module aims to provide a simple unified interface to any stemmer on CPAN.
It will provide a default available source module when a language is requested
but no source is requested.
## Attributes
- language
The following language codes are currently supported.
┌────────────┬────┐
│ Bulgarian │ bg │
│ Czech │ cs │
│ Danish │ da │
│ Dutch │ nl │
│ English │ en │
│ Esperanto │ eo │
│ Finnish │ fi │
│ French │ fr │
│ Galician │ gl │
│ German │ de │
│ Hungarian │ hu │
│ Ido │ io │
│ Italian │ it │
│ Latin │ la │
│ Norwegian │ no │
│ Persian │ fa │
│ Polish │ pl │
│ Portuguese │ pt │
│ Romanian │ ro │
│ Russian │ ru │
│ Spanish │ es │
│ Swedish │ sv │
│ Turkish │ tr │
└────────────┴────┘
They are in the two-letter ISO 639-1 format and are case-insensitive but are
always returned in lowercase when requested.
```perl
# instantiate a stemmer object
$stemmer = Lingua::Stem::Any->new(language => $language);
# get current language
$language = $stemmer->language;
# change language
$stemmer->language($language);
```
The default language is `en` (English). The values `nb` (Norwegian Bokmål)
and `nn` (Norwegian Nynorsk) are aliases for `no` (Norwegian). Country codes
such as `CZ` for the Czech Republic are not supported, as opposed to `cs` for
the Czech language, nor are full IETF language tags or Unicode locale
identifiers such as `pt-PT` or `pt_BR`.
- source
The following source modules are currently supported.
┌────────────────────────┬──────────────────────────────────────────────┐
│ Module │ Languages │
├────────────────────────┼──────────────────────────────────────────────┤
│ Lingua::Stem::Snowball │ da de en es fi fr hu it nl no pt ro ru sv tr │
│ Lingua::Stem::UniNE │ bg cs de fa │
│ Lingua::Stem │ da de en fr gl it no pt ru sv │
│ Lingua::Stem::Patch │ eo io pl │
└────────────────────────┴──────────────────────────────────────────────┘
A module name is used to specify the source. If no source is specified, the
first available source in the above list with support for the current language
is used.
```perl
# get current source
$source = $stemmer->source;
# change source
$stemmer->source('Lingua::Stem::UniNE');
```
- cache
Boolean value specifying whether to cache the stem for each word. This will
increase performance when stemming the same word multiple times at the expense
of increased memory consumption. When enabled, the stems are cached for the life
of the object or until the ["clear\_cache"](#clear_cache) method is called. The same cache is
not shared among different languages, sources, or different instances of the
stemmer object.
- exceptions
Exceptions may be desired to bypass stemming for specific words and use
predefined stems. For example, the plural English word `mice` will not stem to
the singular word `mouse` unless it is specified in the exception dictionary.
Another example is that by default the word `pants` will stem to `pant` even
though stemming is normally not desired in this example. The exception
dictionary can be provided as a hashref where the keys are language codes and
the values are hashrefs of exceptions.
```perl
# instantiate stemmer object with exceptions
$stemmer = Lingua::Stem::Any->new(
language => 'en',
exceptions => {
en => {
mice => 'mouse',
pants => 'pants',
}
}
);
# add/change exceptions
$stemmer->exceptions(
en => {
mice => 'mouse',
pants => 'pants',
}
);
# alternately...
$stemmer->exceptions->{en} = {
mice => 'mouse',
pants => 'pants',
};
```
- casefold
Boolean value specifying whether to apply Unicode casefolding to words before
stemming them. This is enabled by default and is performed before normalization
when also enabled.
- normalize
Boolean value specifying whether to apply Unicode NFC normalization to words
before stemming them. This is enabled by default and is performed after
casefolding when also enabled.
## Methods
- stem
Accepts a list of strings, stems each string, and returns a list of stems. The
list returned will always have the same number of elements in the same order as
the list provided. When no stemming rules apply to a word, the original word is
returned.
```perl
@stems = $stemmer->stem(@words);
# get the stem for a single word
$stem = $stemmer->stem($word);
```
The words should be provided as character strings and the stems are returned as
character strings. Byte strings in arbitrary character encodings are not
supported.
- stem\_in\_place
Accepts an array reference, stems each element, and replaces them with the
resulting stems.
```perl
$stemmer->stem_in_place(\@words);
```
This method is provided for potential optimization when a large array of words
is to be stemmed. The return value is not defined.
- languages
Returns a list of supported two-letter language codes using lowercase letters.
```perl
# all languages
@languages = $stemmer->languages;
# languages supported by Lingua::Stem::Snowball
@languages = $stemmer->languages('Lingua::Stem::Snowball');
```
- sources
Returns a list of supported source module names.
```perl
# all sources
@sources = $stemmer->sources;
# sources that support English
@sources = $stemmer->sources('en');
```
- clear\_cache
Clears the stem cache for all languages and sources of this object instance when
the ["cache"](#cache) attribute is enabled. Does not affect whether caching is enabled.
# SEE ALSO
[Lingua::Stem::Snowball](https://metacpan.org/pod/Lingua::Stem::Snowball), [Lingua::Stem::UniNE](https://metacpan.org/pod/Lingua::Stem::UniNE), [Lingua::Stem](https://metacpan.org/pod/Lingua::Stem), [Lingua::Stem::Patch](https://metacpan.org/pod/Lingua::Stem::Patch)
# AUTHOR
Nick Patch
This project is brought to you by [Shutterstock](http://www.shutterstock.com/).
Additional open source projects from Shutterstock can be found at
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# COPYRIGHT AND LICENSE
© 2013–2014 Shutterstock, Inc.
This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.