Re: [SOLUTION] Current Temperature (#68)
- From: Aditya Mahajan <adityam@xxxxxxxxx>
- Date: Mon, 27 Feb 2006 02:27:46 +0900
<--- On Feb 24, Ruby Quiz wrote --->
by Caleb Tennis
Write a Ruby program such that given a certain argument to the program it
will return the current temperature of that location. People living in
the United States may be interested in temperature by ZIP code:
$ ruby current_temp.rb 47201
The temperature in Columbus, Indiana is 32 degrees F.
Other locales may want to use their own mailing codes, or city names:
$ ruby current_temp.rb madrid
The temperature in Madrid, Spain is 12 degrees C.
Which arguments you support is up to you.
This quiz finally got me going to read Ruby's Net API. It turned out to be very pleasing. Here is my solution.
I use the wunderground website to get the weather. The program supports all kinds of search arguments that are supported by wundergroud. I pass on the input arguments to wu website. If a city is found, the search results contain a link to rss feed. Instead of parsing the html document, I get this rss feed and parse it. This method fails sometimes, for small cities outside US.
Here is the code
# Examples:
# $ current_temp.rb 48105
# > The temperature in Ann Arbor, MI is 34 degrees F / 1 degrees C
#
# $ current_temp.rb Ann Arbor, MI
# > The temperature in Ann Arbor, MI is 34 degrees F / 1 degrees C
#
# $ current_temp DTW
# > The temperature in Detroit Metro Wayne County, MI is 36 degrees F / 2 degrees C
#
# $ current_temp New Delhi, India
# > The temperature in New Delhi, India is 77 degrees F / 25 degrees C
#
# $ current_temp DEL
# > The temperature in New Delhi, India is 77 degrees F / 25 degrees C
#
#--------------------------------------%<--------------------------------------
require 'net/http'
require 'uri'
require 'rexml/document'
if ARGV.length == 0
puts "Usage: ruby current_temp.rb [city, state | zipcode | city, country | airport code]"
exit
end
urlbase = "http://www.wunderground.com/cgi-bin/findweather/getForecast?query=";
zipcode = ARGV.join('%20')
# Search for the zipcode on wunderground website
response = Net::HTTP.get_response URI.parse(urlbase << zipcode)
# Parse the result for the link to a rss feed
rss_feed = String.new
# Get the line with rss feed
response.body.each do |line|
if line.include?("application/rss+xml") then
stop_pos = line.rindex('"') - 1
start_pos = line.rindex('"',stop_pos) + 1
rss_feed = line.slice(start_pos..stop_pos)
break
end
end
# Get the feed and parse it for city and weather information
# The response is different for US cities and places outside US.
# Use appropritate regular expression to parse both simultaneously
if rss_feed == "" then
puts ARGV.join(' ') << ": No such city"
else
feed = Net::HTTP.get_response(URI.parse(rss_feed))
document = REXML::Document.new feed.body
title = document.elements.to_a("//title")[0].text
channel = document.elements.to_a("//channel/item/description")[0].text
city = title.gsub(/\s*(Weather from)?\s*Weather Underground\s*(-)?\s*/,"")
temp = channel.gsub(/(^Temperature:|\|.*$|\W)/,"")
temp = temp.gsub("F", " degrees F / ").gsub("C", " degrees C")
# For exact format as asked in the quiz, uncomment the following
# temp = temp.gsub("F.*$", "F")
puts "The temperature in #{city} is #{temp}"
end
#--------------------------------------%<--------------------------------------
Thanks for the nice quiz.
Aditya
--
Aditya Mahajan, EECS Systems, University of Michigan
http://www.eecs.umich.edu/~adityam || Ph: 7342624008
.
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