Quick Start

とりあえず使ってみよう！

Here's a guide to getting started with MeCab parsing using natto.

This requires:

• Ruby 1.9 or greater
• an existing installation of MeCab with a system dictionary
• either:
  • use automatic configuration: just make sure that mecab (and mecab-config if you are on Mac OS or *nix) are on your PATH
  • or explicit configuration: MECAB_PATH environment variable set to the full path to the mecab library

---

1. First create an instance of a Natto::MeCab parser:

    require 'natto'
   
    nm = Natto::MeCab.new
    => #<Natto::MeCab:0x288f6d08 
         @tagger=#<FFI::Pointer address=0x28d3ab80>,  
         @libpath="/usr/local/lib/libmecab.so",        
         @options={},  
         @dicts=[#<Natto::DictionaryInfo:0x288f6ba0 
                  @filepath="/usr/local/lib/mecab/dic/ipadic/sys.dic", 
                  charset=utf-8,
                  type=0>],  
         @version=0.996>  
   

2. Query the Natto::MeCab parser for its MeCab version and absolute path to MeCab library:

    puts nm.version
    => 0.996
   
    puts nm.libpath
    => /usr/local/lib/libmecab.so  
   

3. Fetch information about the dictionary used by the Natto::MeCab parser:

    puts nm.dicts.first.filepath
    => /usr/local/lib/mecab/dic/ipadic/sys.dic
   
    puts nm.dicts.first.charset
    => utf-8  
   

4. Use the parse method to tokenize a Japanese sentence, treating the result as a single string, and print the output to screen:

    puts nm.parse('この星の一等賞になりたいの卓球で俺は、そんだけ！')
   
    この	連体詞,*,*,*,*,*,この,コノ,コノ
    星	名詞,一般,*,*,*,*,星,ホシ,ホシ
    の	助詞,連体化,*,*,*,*,の,ノ,ノ
    一等	名詞,一般,*,*,*,*,一等,イットウ,イットー
    賞	名詞,接尾,一般,*,*,*,賞,ショウ,ショー
    に	助詞,格助詞,一般,*,*,*,に,ニ,ニ
    なり	動詞,自立,*,*,五段・ラ行,連用形,なる,ナリ,ナリ
    たい	助動詞,*,*,*,特殊・タイ,基本形,たい,タイ,タイ
    の	助詞,連体化,*,*,*,*,の,ノ,ノ
    卓球	名詞,サ変接続,*,*,*,*,卓球,タッキュウ,タッキュー
    で	助詞,格助詞,一般,*,*,*,で,デ,デ
    俺	名詞,代名詞,一般,*,*,*,俺,オレ,オレ
    は	助詞,係助詞,*,*,*,*,は,ハ,ワ
    、	記号,読点,*,*,*,*,、,、,、
    そん	名詞,一般,*,*,*,*,そん,ソン,ソン
    だけ	助詞,副助詞,*,*,*,*,だけ,ダケ,ダケ
    ！	記号,一般,*,*,*,*,！,！,！
    EOS  
   

5. Parse the given text into an enumeration of nodes. By providing a block to parse, a mecab node representing each morpheme and carrying much more detailed information is yielded:

    nm.parse('飛べねえ鳥もいるってこった。') do |n|
      puts "#{n.surface}\t#{n.wcost}" if n.is_nor?
    end
   
    飛べ    7175
    ねえ    6661
    鳥      4905
    も      4669
    いる    9109
    って    6984
    こっ    9587
    た      5500
    。      215  
   

6. Combine node-parsing with a custom node-format for more interesting processing:

    # -F    ... short-form of --node-format
    # %m    ... morpheme
    # %h    ... part-of-speech ID (IPADIC)
    # %f[0] ... part-of-speech (first ChaSen feature element)
    nm = Natto::MeCab.new('-F%m\t%h\t%f[0]')
   
    # only output feature attribute of normal nodes, 
    # ignoring end-of-sentence or unknown nodes
    nm.parse('あんたはオイラに飛び方を教えてくれた。') do |n|
      puts n.feature if n.is_nor?
    end
   
    あんた  59      名詞
    は      16      助詞
    オイラ  59      名詞
    に      13      助詞
    飛び    31      動詞
    方      57      名詞
    を      13      助詞
    教え    31      動詞
    て      18      助詞
    くれ    33      動詞
    た      25      助動詞
    。      7       記号
   

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