Get a "map" of your twitter followers for useful RTs - See which of your followers are following people that you also follow.

follower_map.rb

require "twitter"

# Set sample size (pick this percentage of your followers)
SAMPLE_SIZE = 0.25

# Construct Twitter instance
t = Twitter.new

# Add screenname to params
screen_name = "zthomae"

# Make hash of users screen_name follows, with a count set to zero.
friends = Hash.new(0)
t.friend_ids(screen_name).collection.each { |x| friends[x] = 0 }

# Take a random sample of the users following screen_name, rounded up.
# Discard result if a duplicate or if user is protected.
# TODO?: Authentication (kicking out protected users is questionable)
followers = t.follower_ids(screen_name).collection
num = (followers.size * SAMPLE_SIZE).ceil
sample = Array.new
while sample.size < num
	follower = followers[rand(0..followers.size)]
	sample.push(follower) if (!sample.include?(follower) && !t.user(follower).protected?)
end

# For each of these users, get a list of all of the users they follow.
# If they are in friends, increment their counter.
sample.each do |x|
	f_friends = t.friend_ids(t.user(x)).collection
	f_friends.each do |y|
		friends[y] += 1 if !friends.include?(y)
	end
end

# Sort friends by counter value. Print final results.
friends = friends.sort_by { |key, value| value }
friends.each { |x| puts x.to_s }