From: Harry Ohlsen <harryo@...>
Date: 2002-11-21T08:25:26+09:00
Subject: Sydney Ruby users' group meeting tonight!


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Hi People,

Well, I've been very slack ... as usual, some are saying :-).  I've been=20
studying for exams, so my mind's been elsewhere recently.

I went to the trouble of organising a separate mailing list earlier this =
week,=20
waited a while to give people a chance to subscribe and then forgot to se=
nd a=20
reminder to it !!

Anyway, tonight is the monthly meeting.  As usual, it's upstairs at the=20
Woolloomooloo Bay Hotel at 6pm.

Martin Stannard made the suggestion that we could set up a simple program=
ming=20
problem and discuss how different people went about attacking it.  Since =
I've=20
left this so late, it's probably not going to be much use for tonight, bu=
t=20
I've attached some code and a URL at the end, if people feel like having =
a=20
go.

My thought was that we could use the things that were discussed at the=20
conference earlier this month as a starting point.  Things like FreeRIDE,=
=20
TaskMaster, Perl idioms in Ruby, NARF, Parrot, web scripting using=20
continuations, YAML.

Also, Martin said that if we can't find anything else to discuss, he'll g=
o=20
into some of the details of his horse genealogy system.

I'm not sure whether I'll make it this month due to study.  If not, I'll =
see=20
you all at the next meeting.

At least I won't get drunk and ask again what weak references are used fo=
r :-)

As promised, here's the URL for the problem Martin suggested ...

       http://www.cs.ualberta.ca/~darse/rsbpc.html

It's a roshambo (ie, "paper, rock, scissors") game where you write your o=
wn=20
player and compete against others.  The attached code is a Ruby=20
implementation that Martin wrote.

Cheers,

Harry O.

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$PossibleMoves = %w{rock paper scissors}
$Rock = 0
$Paper = 1
$Scissors = 2
$Round = 0

def biased_roshambo(prob_rock, prob_paper)
	throw = rand()
	return $Rock if throw < prob_rock
	return $Paper if throw < prob_rock + prob_paper
	$Scissors
end

class Player

	attr_reader :history, :currentMove, :name
	attr_accessor :totalWins, :rounds

	def initialize
		clear
		@totalWins = 0
		@rounds = 0
		@name = self.class.to_s
	end

	def clear
		@history = []
		@currentMove = nil
	end

	def move(opponent)
		@rounds += 1.0
		@currentMove = make_move(opponent)
	end

	def record_move
		@history.push(@currentMove)
	end

end

class RockPlayer < Player

	def make_move(opponent)
		$Rock
	end

end

class RandPlayer < Player

	def make_move(opponent)
		rand($PossibleMoves.size)
	end

end

class R226Player < Player

	def make_move(opponent)
		biased_roshambo(0.2, 0.2)
	end

end

class RotatePlayer < Player

	def make_move(opponent) 
		return rand(3) if @history.last.nil? 
		(@history.last + 1).modulo(3)
	end

end

class CopyPlayer < Player

	def make_move(opponent) 
		return rand(3) if !opponent.history.last 
		(opponent.history.last + 1).modulo(3)
	end

end


class SwitchPlayer < Player

	def make_move(opponent)
		return rand(3) if @history.last.nil?
		return biased_roshambo(0.0, 0.5) if history.last == $Rock
		return biased_roshambo(0.5, 0.0) if history.last == $Paper
		return biased_roshambo(0.5, 0.5)
	end

end

class FreqPlayer < Player

	def make_move(opponent)
		i, r, p, s = 0, 0, 0, 0
		$Round.times do |t|
			case opponent.history[t]
			when $Rock then r += 1
			when $Paper then p += 1
			when $Scissors then s += 1
			end
		end
		return $Paper if r > p && r > s
		return $Scissors if p > s
		return $Rock
	end

end

class Freq2Player < Player

	def initialize
	    super
	    @i, @r, @p, @s = 0, 0, 0, 0
	end

	def make_move(opponent)
	    if !opponent.history.last.nil?
		    opp_last = opponent.history.last
		    case opponent.history.last
		    when $Rock then @r += 1
		    when $Paper then @p += 1
		    when $Scissors then @s += 1
		    end
	    end
	    return $Paper if @r > @p && @r > @s
	    return $Scissors if @p > @s
	    return $Rock
	end

end

class SwitchALotPlayer < Player

	def make_move(opponent)
		return rand(3) if @history.last.nil?
		return biased_roshambo(0.12, 0.44) if @history.last == $Rock
		return biased_roshambo(0.44, 0.12) if @history.last == $Paper
		return biased_roshambo(0.44, 0.44) if @history.last == $Scissors
	end

end

$Players = [RockPlayer.new, RandPlayer.new, R226Player.new, CopyPlayer.new, RotatePlayer.new, SwitchPlayer.new, FreqPlayer.new, Freq2Player.new, SwitchALotPlayer.new, HarryO.new]

class Tournament

	def run
		$Players.each do |p1|
			$Players.reverse.each do |p2|
				if p1 != p2
					battle(p1, p2, 1000)
				end
			end
		end
		$Players.sort! { |p1, p2| p2.totalWins <=> p1.totalWins }
		puts "-----------------------------------------"
		$Players.each do |p| 
			print "#{p.name.ljust(20)} #{p.totalWins.to_s.rjust(6)}"
			puts "  #{p.totalWins/p.rounds*100}"
		end
	end

	def winner(p1, p2)
		return "tie" if p1 == p2
		return "p1" if p1 == $Rock && p2 == $Scissors
		return "p2" if p2 == $Rock && p1 == $Scissors
		return "p1" if p1 == $Paper && p2 == $Rock
		return "p2" if p2 == $Paper && p1 == $Rock
		return "p1" if p1 == $Scissors && p2 == $Paper
		return "p2" if p2 == $Scissors && p1 == $Paper
	end

	def do_round(p1, p2)
		victor = winner(p1.move(p2), p2.move(p1))
		p1.record_move
		p2.record_move
		victor
	end

	def battle(p1, p2, rounds)
		puts "Battle between #{p1.name} and #{p2.name}"
		p1wins = 0
		p2wins = 0
		p1.clear
		p2.clear
		rounds.times do |t|
			victor = do_round(p1, p2)
			case victor
			when 'p1' 
				p1wins += 1
				p1.totalWins += 1
			when 'p2' then 
				p2wins += 1
				p2.totalWins += 1
			end
			$Round = t 
		end
		puts "#{p1.name} won: [#{p1wins}] #{p2.name} won: [#{p2wins}]"
	end

end

t = Tournament.new
t.run



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