Ruby script to use Mecab via natto gem

mecab.rb

#!/usr/bin/env ruby
require 'natto'
require 'pp'

nm = Natto::MeCab.new

morph = []
while line = $stdin.gets
  nm.parse(line) {|n|
    next unless n.is_nor? || n.is_unk?

    p, pd, _, _, _, _, of = n.feature.split(',')

    next if p =~ /^助動?詞|記号$/
    next if p == '名詞' && pd == '数'

    morph << [
      ( of == '*' ? n.surface : of ), # Original form
      p,  # Parse
      pd, # Parse (detail)
      case true
      when n.is_nor?
        '通常'  # well-known morpheme (= in dictionary word)
      when n.is_unk?
        '未知語'
      end
    ]
  }
end

pp morph.group_by {|i| i}.inject([]) {|a, i| a << [ i[0], i[1].count ] }.sort_by {|v| [v[1]*-1, *v[0]] }