class EloManager

Attributes

k_factor[RW]

Public Class Methods

new() click to toggle source

# File lib/multiplayer_elo/elo_manager.rb, line 4
def initialize
        @k_factor = 20
end

Public Instance Methods

evaulate_results(results) click to toggle source

# File lib/multiplayer_elo/elo_manager.rb, line 17
def evaulate_results(results)
        results.each do |i|
                elo_change = 0
                results.each do |j|
                        next if i == j
                        
                        # we are using places so first place < 2nd place means a win
                        if i[:place] > j[:place]
                                winner = 0
                        elsif i[:place] == j[:place]
                                winner = 0.5
                        else
                                winner = 1
                        end

                        elo_change += points_change(i[:elo], j[:elo], winner)
                end

                i[:new_elo] = i[:elo] + elo_change
        end
end

expected_percentage(elo1, elo2) click to toggle source

# File lib/multiplayer_elo/elo_manager.rb, line 8
def expected_percentage(elo1, elo2)
        1.0 / ( 1.0 + ( 10.0 ** ((elo2.to_f - elo1.to_f) / 400.0) ) )
end

points_change(elo1, elo2, result) click to toggle source

result is 0 for a loss 1 for a win or .5 for a tie

# File lib/multiplayer_elo/elo_manager.rb, line 13
def points_change(elo1, elo2, result)
        (@k_factor.to_f * (result.to_f - expected_percentage(elo1, elo2))).round
end