the weather

gistfile1.rb

require 'rubygems'
require 'nokogiri'
require 'open-uri'
require 'RMagick'

def retrieve_image(url)
  data = open(url).read
  data
end

def composite(img, dest_image_data)
  if dest_image_data.nil? then
    return img
  end
  
  begin
    tmp_img = Magick::Image.from_blob(dest_image_data).first
    if img == nil then
      img = tmp_img
    else
      img = img.composite(tmp_img, Magick::CenterGravity, Magick::OverCompositeOp)
    end
  rescue
    puts "error"
  end
  img
end

radar_id = ARGV[0]
if radar_id.nil? || radar_id.length != 3 then
  puts "usage: radar <identifier>"
  exit
end

html = Nokogiri::HTML(open("http://radar.weather.gov/radar.php?rid=#{radar_id}"))

#get map
map_graphics = html.xpath("//div[@id='bkgrnd']//img")

img = nil
map_graphics.each() do |graphic|
  #src
  url = graphic['src']
  #check for nothing
  if url[0..1] != '#' then
    #get it
    data = retrieve_image("http://radar.weather.gov/#{url}")
    img = composite(img, data)
  end
end

#get radar
radar_img = retrieve_image("http://radar.weather.gov/RadarImg/N0R/#{radar_id}_N0R_0.gif")
img = composite(img, radar_img)
radar_legend = retrieve_image("http://radar.weather.gov/Legend/N0R/#{radar_id}_N0R_Legend_0.gif")
img = composite(img, radar_legend)

img.write('radarimage.png')