漢字混じりの文字列をローマ字列に変換する。input.txt(改行区切り)を読み込んでoutput.txtに吐き出す。YahooAPIを利用。

Gemfile

# A sample Gemfile
source "https://rubygems.org"

# gem "rails"
gem "yahoo-japanese-analysis"
gem "romaji"

rubifuri.rb

require 'yahoo-japanese-analysis'
require 'romaji'
require 'pp'

data = File.read('./sample.txt').split("\n");

YahooJA.configure do |config|
  config.app_key = 'dj0zaiZpPTlhNTluRTM1MGFZeSZzPWNvbnN1bWVyc2VjcmV0Jng9NWY-'
end

result = []

puts "requesting..."

data.each { |str|
  puts str
  res = YahooJA.furigana(str)
  pp res
  next if res.nil?
  kana = [res[:Result][:WordList][:Word]].flatten.inject('') { |r, v_|
    add = v_[:Furigana] ? v_[:Furigana] : v_[:Surface]
    r + add
  }
  puts kana
  romaji = Romaji.kana2romaji(kana)
  puts romaji
  result << romaji
}

File.write('output.txt', result.join("\n"))