to_one_mode.rb

#require 'set'

infile = "facebook_users_to_youtube_ids_unique.gdf"
outfile = "facebook_users_edges_youtube_network.gdf.part"

users = Hash.new([])
youtube_ids = Hash.new([])
friendships = Hash.new([])

File.open(infile).each do |line|
  user_id, youtube_id = line.chomp.split(",")
  user_id = user_id.to_i
  users[user_id] = users[user_id] | [youtube_id]
  youtube_ids[youtube_id] = youtube_ids[youtube_id] | [user_id]
end
puts "found #{users.size} users and #{youtube_ids.size} youtube_ids"


users.keys.each do |uid|
  users[uid].each do |ytid|
    (youtube_ids[ytid] - [uid]).each do |same_taste_friend_id|
      left_node, right_node = [uid,same_taste_friend_id].sort
      friendships[left_node] = friendships[left_node] | [right_node]
    end
  end  
end


ofhandle = open(outfile, "w")
puts "sorted #{friendships.count} friendships"

friendships.each do |left_node, right_nodes|
  right_nodes.each do |right_node|
     ofhandle.puts( [left_node, right_node].sort.join(","))
  end
end

ofhandle.close