src/.svn/text-base/selection.rb.svn-base

   1 # == Synopsis
   2 #
   3 # Use a GA to breed a good potential player
   4 #
   5 # == Author
   6 # Neil Smith
   7 #
   8 # == Change history
   9 # Version 1.1::  23 April 2008
  10
  11
  12 require 'libttc'
  13 require 'libpplayer'
  14 require 'libgenetics'
  15 require 'play'
  16
  17 class Population
  18   # Use tournament selection to pick an individual for the next generation
  19   def tournament_select_one(winner_success_chance = 0.8, max_game_length= 1000, verbose = false)
  20     player_count = rand(5) + 2
  21     pool_size = @individuals.length
  22     players = []
  23     1.upto(player_count) { players << @individuals[rand(pool_size)].to_potential_player }
  24     game = GameHandler.new(players, max_game_length, false, false)
  25     winner, length = game.play
  26     puts "Winner = #{winner} in #{length} moves.  Game had #{player_count} players" if verbose
  27     # If the game was a draw, or the winner is unlucky, pick a parent at random
  28     if winner == :draw or rand > winner_success_chance
  29       successful_player = players[rand(player_count)]
  30     else
  31       successful_player = winner
  32     end
  33     successful_player
  34   end
  35
  36   # Select a new population the same size as the current population
  37   def tournament_select_population(winner_success_chance = 0.8, max_game_length = 1000, verbose = false)
  38     new_population = []
  39     1.upto(@individuals.length) do
  40       new_population << tournament_select_one(winner_success_chance, max_game_length, verbose).to_genome
  41       puts "Created #{new_population.length} indivduals" if verbose
  42     end
  43     new_population
  44   end
  45
  46 end
  47
  48 class Potential_player
  49   # Convert a player to a bitstring
  50   def to_bitstring
  51     (@friend_pull * 4).to_i.to_bitstring(4).gray_encode +
  52       (@enemy_pull * 4).to_i.to_bitstring(4).gray_encode +
  53       (@base_pull * 4).to_i.to_bitstring(4).gray_encode +
  54       @safe_bonus.to_bitstring(4).gray_encode +
  55       @capture_bonus.to_bitstring(4).gray_encode
  56   end
  57
  58   # Convert a player to a genome
  59   def to_genome
  60     Genome.new(self.to_bitstring)
  61   end
  62 end
  63
  64
  65 class Genome
  66
  67   # Create a potential player from a genome
  68   def to_potential_player
  69     friend_pull   = @genome[0,  4].gray_decode.to_decimal.to_f / 4
  70     enemy_pull    = @genome[4,  4].gray_decode.to_decimal.to_f / 4
  71     base_pull     = @genome[8,  4].gray_decode.to_decimal.to_f / 4
  72     safe_bonus    = @genome[12, 4].gray_decode.to_decimal
  73     capture_bonus = @genome[16, 4].gray_decode.to_decimal
  74     Potential_player.new({:friend_pull => friend_pull,
  75         :enemy_pull => enemy_pull, :base_pull => base_pull,
  76         :safe_bonus => safe_bonus, :capture_bonus => capture_bonus})
  77   end
  78 end