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Ruby-Stemmer exposes SnowBall API to Ruby.

This package includes libstemmer_c library released under BSD licence and available for free here.

Support for latin language is also included and it has been generated with the snowball compiler using schinke contribution.

For more details about libstemmer_c please visit the SnowBall website.


require 'rubygems'
require 'lingua/stemmer'

stemmer= => "ro")
stemmer.stem("netăgăduit") #=> netăgădu


require 'rubygems'
require 'lingua/stemmer'

Lingua.stemmer( %w(incontestabil neîndoielnic), :language => "ro" ) #=> ["incontest", "neîndoieln"]
Lingua.stemmer("installation") #=> "instal"
Lingua.stemmer("installation", :language => "fr", :encoding => "ISO_8859_1") do | word |
  puts "~> #{word}" #=> "instal"
end # => #<Lingua::Stemmer:0x102501e48>


# Rails2: -- config/environment.rb:
config.gem 'ruby-stemmer', :version => '>=0.6.2', :lib => 'lingua/stemmer'

# Rails3: -- Gemfile
gem 'ruby-stemmer', '>=0.8.3', :require => 'lingua/stemmer'

More details


Standard install with:

gem install ruby-stemmer


There's also a Windows (Fat bin) compiled against ruby versions: 1.8.7, 1.9.3, 2.1.5, 2.2.0

gem install ruby-stemmer --platform=x86-mingw32

As far as I know the above should work with rubyinstaller. If if fails, you could try with:

gem install ruby-stemmer --platform=x86-mswin32

It’s known to work under Windows XP.

Development version

$ git clone git://
$ cd ruby-stemmer
$ rake -T #<== see what we've got
$ rake compile #<== builds the extension do'h
$ rake test

Cross Compiling

Install rake-compiler-dev-box and follow the setup. Inside vagrant box run:

$ cd /vagrant
$ RUBY_CC_VERSION=1.8.7:1.9.3:2.1.5:2.2.0 package_win32_fat_binary ruby-stemmer

Idea is to have same builds as in travis.yml.


The stemming process is an algorithm to allow one to find the stem of an word (not the root of it). For further reference on stem vs. root, please check wikipedia articles on the topic:


Note on Patches/Pull Requests

  • Fork the project from github

  • Make your feature addition or bug fix

  • Add tests for it. This is important so I don't break it in a future version unintentionally.

  • Commit, do not mess with rakefile, version, or history.

    if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull

  • Send me a pull request. Bonus points for topic branches.

Alternative Stemmers for Ruby


Copyright © 2008-2015 Aurelian Oancea. See MIT-LICENSE for details.


Real life usage

  • is using Ruby-Stemmer together with Classifier to automatically rate places based on users comments.

# encoding: utf-8