git.oblomov.eu Git - milivella/blob - milivelo.rb

   1 #!/usr/bin/ruby
   2
   3 # Author: Giuseppe "Oblomov" Bilotta <giuseppe.bilotta@gmail.com>
   4 # License: GPLv2
   5
   6 # Quick & dirty script to calculate ELO rankings. See later of input format.
   7
   8 class Rating
   9         # customizable
  10         BASE_RATING=1500
  11
  12         # K factor, can be either fixed, or staircased, or some other function
  13         def fixedK(score)
  14                 # customizable
  15                 16
  16         end
  17
  18         def rangedK(score)
  19                 # customizable
  20                 case score
  21                 when 0..2100
  22                         32
  23                 when 2100..2400
  24                         24
  25                 else
  26                         # > 2400
  27                         16
  28                 end
  29         end
  30
  31         def funcK(score)
  32                 # customizable
  33                 32 - Math.log(2400)
  34         end
  35
  36         # choose the one we want here
  37         alias :factor :fixedK
  38
  39         attr_reader :rating
  40         def initialize
  41                 # the player list is a hash player => rating that defaults to the base rating
  42                 @rating = Hash.new { |h, k| h[k] = BASE_RATING }
  43         end
  44
  45         def [](k)
  46                 @rating[k.to_sym]
  47         end
  48
  49
  50         def to_s
  51                 rating.to_a.sort { |a, b| b.last <=> a.last }.map { |a| a.join(': ') }.join("\n")
  52         end
  53
  54         def update(winner, loser, draw=false)
  55                 diff = rating[loser] - rating[winner]
  56                 winner_wins = 1.0/(Math.exp(diff/174)+1)
  57                 loser_wins = 1.0 - winner_wins
  58                 score = 1.0
  59                 score -= 0.5 if draw
  60                 rating[winner] += factor(rating[winner])*(score - winner_wins)
  61                 rating[loser] += factor(rating[loser])*(1.0 - score - loser_wins)
  62         end
  63 end
  64
  65 # read lines from standard input, skipping lines that start with a has sign (#)
  66 # each match line is supposed to be in the form:
  67 # player1 <=> player2
  68 # where <=> is < if player2 won, > if player1 won, = if the match was a draw.
  69 # 2, 1, x are also accepted instead of <, > and = respectively.
  70 # Lines in the form:
  71 # player1,player2,<=>
  72 # are accepted too.
  73
  74 # The player names should have no spaces in them, and anything after the name
  75 # of the second player is ignored
  76
  77 rating = Rating.new
  78 $stdin.each_line do |line|
  79         # strip comments
  80         line.sub!(/#.*/,'')
  81                 # strip whitespace
  82                 line.strip!
  83         next if line.empty?
  84         player1, sign, player2, junk = line.split($;,4)
  85         unless sign
  86                 player1, player2, sign = line.split(/\s*,\s*/,3)
  87         end
  88         case sign
  89         when '2', '<'
  90                 rating.update(player2.intern, player1.intern)
  91         when 'x', 'X', '='
  92                 rating.update(player2.intern, player1.intern, true)
  93         when '1', '>'
  94                 rating.update(player1.intern, player2.intern)
  95         else
  96                 raise "wrong match sign #{sign.inspect}"
  97         end
  98         puts "%s,%s,%s,%f,%f" % [player1, player2, sign, rating[player1], rating[player2]]
  99 end
 100
 101 puts
 102 puts rating.to_s