understanding Ruby code? - ruby

Question

I was wondering if anyone can help me understanding the Ruby code below? I'm pretty new to Ruby programming and having trouble understanding the meaning of each functions.
When I run this with my twitter username and password as parameter, I get a stream of twitter feed samples. What do I need to do with this code to only display the hashtags?
I'm trying to gather the hashtags every 30 seconds, then sort from least to most occurrences of the hashtags.
Not looking for solutions, but for ideas. Thanks!
require 'eventmachine'
require 'em-http'
require 'json'
usage = "#{$0} <user> <password>"
abort usage unless user = ARGV.shift
abort usage unless password = ARGV.shift
url = 'https://stream.twitter.com/1/statuses/sample.json'
def handle_tweet(tweet)
return unless tweet['text']
puts "#{tweet['user']['screen_name']}: #{tweet['text']}"
end
EventMachine.run do
http = EventMachine::HttpRequest.new(url).get :head => { 'Authorization' => [ user, password ] }
buffer = ""
http.stream do |chunk|
buffer += chunk
while line = buffer.slice!(/.+\r?\n/)
handle_tweet JSON.parse(line)
end
end
end

Answer 1

puts "#{tweet['user']['screen_name']}: #{tweet['text']}"
That line shows you a user name followed by the content of the tweet.
Let's take a step back for a sec.
Hash tags appear inside the tweet's content--this means they're inside tweet['text']. A hash tag always takes the form of a # followed by a bunch of non-space characters. That's really easy to grab with a regex. Ruby's core API facilitates that via String#scan. Example:
"twitter is short #foo yawn #bar".scan(/\#\w+/) # => ["#foo", "#bar"]
What you want is something like this:
def handle_tweet(tweet)
return unless tweet['text']
# puts "#{tweet['user']['screen_name']}: #{tweet['text']}" # OLD
puts tweet['text'].scan(/\#\w+/).to_s
end
tweet['text'].scan(/#\w+/) is an array of strings. You can do whatever you want with that array. Supposing you're new to Ruby and want to print the hash tags to the console, here's a brief note about printing arrays with puts:
puts array # => "#foo\n#bar"
puts array.to_s # => '["#foo", "#bar"]'

Answer 2

#Load Libraries
require 'eventmachine'
require 'em-http'
require 'json'
# Looks like this section assumes you're calling this from commandline.
usage = "#{$0} <user> <password>" # $0 returns the name of the program
abort usage unless user = ARGV.shift # Return first argument passed when program called
abort usage unless password = ARGV.shift
# The URL
url = 'https://stream.twitter.com/1/statuses/sample.json'
# method which, when called later, prints out the tweets
def handle_tweet(tweet)
return unless tweet['text'] # Ensures tweet object has 'text' property
puts "#{tweet['user']['screen_name']}: #{tweet['text']}" # write the result
end
# Create an HTTP request obj to URL above with user authorization
EventMachine.run do
http = EventMachine::HttpRequest.new(url).get :head => { 'Authorization' => [ user, password ] }
# Initiate an empty string for the buffer
buffer = ""
# Read the stream by line
http.stream do |chunk|
buffer += chunk
while line = buffer.slice!(/.+\r?\n/) # cut each line at newline
handle_tweet JSON.parse(line) # send each tweet object to handle_tweet method
end
end
end
Here's a commented version of what the source is doing. If you just want the hashtag, you'll want to rewrite handle_tweet to something like this:
handle_tweet(tweet)
tweet.scan(/#\w/) do |tag|
puts tag
end
end