matching_algo.rb

=begin
This is my current matching algorithm.  It's very database-heavy - with this number of records...

>> User.count
=> 25
>> Kink.count
=> 76
>> Rating.count
=> 1900

...it takes about 3000ms to return on my Mac.  This is a bit ugly, and it'll only get worse with more users, kinks and the ratings that'll then be produced.

HALP.

I can be contacted at [email protected] (Jabber and MSN are also available at this address).
=end

  def top
    matches = {}                                                                                                # Initialise empty Hash
    my_ratings = @current_user.ratings                                                                          # Load this user's ratings into my_ratings as my_rating
    User.all.each do |iterated_user|                                                                            # Iterate through all users as iterated_user
      kinks_in_common = 0                                                                                       # # Initialise number of common interests to 0 for this user
      iterated_user_diff_factor = 0                                                                             # # Initialise difference factor to 0 for this user
      my_ratings.each do |iterated_my_rating|                                                                   # # Iterate through all of my ratings
        if (their_rating = Rating.find_by_user_id_and_kink_id(iterated_user.id, iterated_my_rating.kink_id))    # # # If they have a rating for the interest that my_rating is about...
          kinks_in_common += 1                                                                                  # # # # Add 1 to the common interest tally
          iterated_user_diff_factor += (their_rating.rating_as_top - iterated_my_rating.rating_as_bottom).abs   # # # # Add any difference in rating to the difference factor one way round
          iterated_user_diff_factor += (their_rating.rating_as_bottom - iterated_my_rating.rating_as_top).abs   # # # # Add any difference in rating to the difference factor the other way round
        end                                                                                                     # # # End If
      end                                                                                                       # # Next of my ratings, or stop iterating through my ratings
      if kinks_in_common == 0                                                                                   # # # If the two users have nothing in common...
        iterated_user_match_percentage = 0                                                                      # # # # We can't calculate any match, so set the match percentage to 0 
      else                                                                                                      # # # Else (if the users have at least one interest in common)
        iterated_user_match_factor = (kinks_in_common * 6) - iterated_user_diff_factor                          # # # # Take the difference between the maximum possible difference factor (ratings are integers between 0 and 6 inclusive) and the actual difference factor to get the match factor
        iterated_user_match_percentage = ((iterated_user_match_factor.to_f / (kinks_in_common * 6)) * 100).to_i # # # # Convert the match factor to a percentage match (integer 0-100 inclusive)
      end                                                                                                       # # # End If
      matches[iterated_user.id] = iterated_user_match_percentage                                                # # Push the user ID and the match percentage integer into the matches Hash
    end                                                                                                         # End iterating through all users
    matches.delete(@current_user.id)                                                                            # Remove my user ID from the matches Hash
    @topmatches = matches                                                                                       # Pop the matches Hash into the class variable that the view will use
    # @topmatches returns a Hash of uid => match_percentage.                                                    # Remind myself what the hell I've just done
  end