choseki.rb

# encoding: UTF-8

module Choseki
  
  require 'nokogiri'
  require 'open-uri'
  require 'date'
  
  HEADER = ['Time', 'Height']
  
  def get_monthly_data(area, date)
    
    time = []
    height = []
    
    url = "http://www1.kaiho.mlit.go.jp/KANKYO/TIDE/cgi-bin/tide_pred.cgi?area=#{area}&back=./&year=#{date.year}&month=#{date.month}&day=#{date.day}&btn=ForAreaWindow_Japanese"
    
    open(url) do |data|
      
      doc = Nokogiri::HTML(data)
      
      count = 0
      doc.xpath('//tr').each do |tr|
        row = tr.xpath('td[@width="40"]').map { |td| td.content.to_i }
        
        if count % 2 == 1
          time += row.map! { |hour| DateTime.new(date.year, date.month, date.day, hour, 0, 0, Rational(9, 24)) }
        else
          height += row
        end
        
        count += 1
      end
      
      alist = [time, height].transpose
      Hash[alist.flatten(0)]
    end
    
  end
  
  module_function :get_monthly_data
end

require 'date'
require 'csv'

area = 166
first_day = Date.new(2011, 8, 1)
days = 1
file_name = 'akkeshi_2011_8.csv'

dates = []
days.times do |i|
  dates << first_day + i
end

CSV.open(file_name, 'w:UTF-8', headers: true) do |csv|
  csv << Choseki::HEADER
  dates.each do |date|
    Choseki.get_monthly_data(area, date).each do |key, value|
      csv << [key, value]
    end
  end
  sleep 1
end