add examples/elo_tourney.rb

Author: rickhull

examples/elo_tourney.rb

@@ -0,0 +1,136 @@
+require 'compsci/elo'
+
+include CompSci
+
+# return two different integers 0..(pool.count -1)
+def pool_matchup(pool)
+  a = rand(pool.count)
+  [a, (a + rand(pool.count - 1) + 1) % pool.count]
+end
+
+# sum / divide / round
+def avg_rating(pool)
+  (pool.map(&:rating).sum.to_f / pool.count).round
+end
+
+class Array
+  # reverse sort
+  def rank
+    sort { |a, b| b <=> a }
+  end
+end
+
+pool_size = 999
+pool_matchups = 99_999
+tourney_size = 64
+iters = 5
+
+# randomize skill levels
+pool = Elo::Player.init_pool(pool_size).each { |player|
+  player.skill = rand.round(3)
+}
+
+# LETS GO
+
+iters.times { |i|
+  puts
+  puts
+  puts "=" * 40
+  puts "               Season #{i + 1}"
+  puts "=" * 40
+
+  # pool matchups
+  pool_matchups.times {
+    a, b = pool_matchup(pool)
+    pool[a].simulate(pool[b]) # win / lose / draw
+  }
+  pool = pool.rank
+  puts "Ran #{pool_matchups} matchups; average rating: #{avg_rating(pool)}"
+
+  # bottom 5% of pool retires
+  rc = pool_size / 20
+  (pool.count - rc).upto(pool.count - 1) { |i|
+    pool[i] = Elo::Player.new(skill: rand.round(3))
+  }
+  puts "Retired the bottom 10%; average rating: #{avg_rating(pool)}"
+
+  # take top 64 for the tournament
+  puts
+  puts "Top 64:"
+  puts '---'
+  tpool = pool.take(tourney_size).each { |p| puts p }.shuffle
+  puts
+
+  # run the tournament
+  while tpool.size > 1
+    puts "Players: #{tpool.size}"
+    puts '---'
+    next_round = []
+
+    # evens play odds
+    (tpool.size / 2).times { |i|
+      a = i * 2
+      b = a + 1
+      puts format("%s    vs    %s", tpool[a], tpool[b])
+
+      # best 4 out of 7
+      wins, losses = 0, 0
+      while (wins < 4 and losses < 4) or (wins == losses)
+        outcome = tpool[a].simulate(tpool[b])
+        if outcome == 0.5
+          wins += 0.5
+          losses += 0.5
+        elsif outcome < 0.5
+          losses += 1
+        else
+          wins += 1
+        end
+      end
+      if wins > losses
+        outcome, winner = 1, tpool[a]
+      else
+        outcome, winner = 0, tpool[b]
+      end
+      next_round << winner
+      puts "Outcome: #{outcome}\tWinner: #{winner}"
+      puts
+    }
+    puts
+    tpool = next_round
+  end
+
+  # a few pros retire
+  retired = Set.new
+  3.times { retired.add(rand(tourney_size)) }
+  puts "Retired: #{retired.sort.join(', ')}"
+  retired.each { |i|
+    print pool[i]
+    pool[i] = Elo::Player.new(skill: rand.round(3))
+    puts "  ->  #{pool[i]}"
+  }
+  puts
+
+  # 5% non-pros retire
+  retired = Set.new
+  (pool_size / 20).times {
+    retired.add(rand(pool_size - tourney_size) + tourney_size)
+  }
+  puts "Retired: #{retired.sort.join(', ')}"
+  retired.each { |i|
+    pool[i] = Elo::Player.new(skill: rand.round(3))
+  }
+
+  pool = pool.rank
+  puts "Average rating: #{avg_rating(pool)}"
+  puts
+}
+
+# pool matchups
+pool_matchups.times {
+  a, b = pool_matchup(pool)
+  pool[a].simulate(pool[b]) # win / lose / draw
+}
+pool = pool.rank
+puts "Ran #{pool_matchups} matchups; average rating: #{avg_rating(pool)}"
+
+puts pool