using mecab

gistfile1.rb

require 'MeCab'
require 'kconv'

class MecabParser
  def initialize(param = nil)
    @mecab = param ? MeCab::Tagger.new(param) : MeCab::Tagger.new
  end

  def parse(str)
    @mecab.parse(str).split(/\n/).inject([]) do |data, line|
      target, params = {}, line.split(/,|\s/).map(&:toutf8)
      target[:data] = params[0]
      target[:type] = params[1]
      data << target if target[:type]
      data
    end
  end

  class << self
    def parse(str, options = {})
      mecab = self.new(options.delete(:param))
      type, duplicate_count = options.delete(:type), options.delete(:duplicate_count)

      result = mecab.parse(str)
      result = result.select{|data| data[:type] == type } if type
      result = result.inject([]) do |store, data|
        unless position = store.index{|store_data| store_data[:data] == data[:data] }
          store << data.merge(:count => 1)
        else
          store[position][:count] += 1
        end
        store
      end if duplicate_count
      result
    end
  end
end

p MecabParser.parse("すもももももももものうち", :type => "助詞")
p MecabParser.parse("すもももももももものうち", :type => "名詞", :duplicate_count => true)