ttagger.rb 2.69 KB
#!/usr/bin/env ruby

# This file is a part of an Information Retrieval oriented Ruby library
#
# Copyright (C) 2010-2011 Romain Deveaud <romain.deveaud@gmail.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

module RIR

  # TreeTagger-related stuff module.
  #
  # See http://www.ims.uni-stuttgart.de/projekte/corplex/TreeTagger/DecisionTreeTagger.html
  module TreeTagger
    
    # This class handles generic parsing of tagger-chunker outputs.
    class TaggerChunker
      attr_reader :chunks, :file


      # Parses a tagger-chunker output and returns an Array of Chunk.
      def self.parse chunk_lines
        open = false
        tag  = nil

        chunks = []
        words  = []

        chunk_lines.each do |l|
          l.chomp!
          if l =~ /^<\w+>$/
            open = true
            tag  = l
          elsif l =~ /^<\/\w+>$/
            if !words.empty? && open && l == tag.sub(/</, '</')
              open = false
              chunks.push Chunk.new(words.join(" "), tag) 
              words.clear
            else
              next
            end
          else
            words.push(l.split.first)
          end
        end

        chunks
      end

      # Initializes parsing. +chunk_file+ is the output of +tagger-chunker-+ and must
      # be a valid path to the file.
      #
      #   TaggerChunker.new("ttout/2010020") #=> #<RIR::TreeTagger::TaggerChunker:0x92fd088 @chunks=[#<RIR::TreeTagger::Chunk:0x8ec5a10 @words=["robert", "schumann"], @tag="NC">, ...] ...>
      def initialize chunk_file
        @chunks = TaggerChunker.parse File.open(chunk_file).readlines
      end

    end

    class TaggerChunkerEnglish < TaggerChunker
    end

    class TaggerChunkerFrench  < TaggerChunker
    end

    class TaggerChunkerGerman  < TaggerChunker
    end

    # Represents a Chunk extracted when parsing a TaggerChunker file.
    class Chunk
      attr_reader :words, :tag

      # +str+ are whitespace-separated terms.
      # +tag+ see : ftp://ftp.ims.uni-stuttgart.de/pub/corpora/chunker-tagset-english.txt
      def initialize str,tag
        @words = str.split
        @tag   = tag[1..-2]
      end
    end

  end
end