Euchre Hands (#55)

james · November 18, 2005, 2:33pm

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The card game of Euchre has an unusual ordering of cards in the hand.
This
week’s Ruby Q. is to take a random Euchre hand and sort it.

The first thing you need to know is that Euchre is played with a small
deck of
cards. Four suits are used Diamonds (d), Clubs (c), Spades (s), and
Hearts (h),
but each suit has only the cards Nine (9), Ten (T), Jack (J), Queen (Q),
King
(K), and Ace (A). The cards are generally ordered as I just listed
them, Nine
being the low card and Ace the high card. The exception is the
“Bowers”.

When a Euchre hand is started, the first task is to select a Trump suit.
How
that’s done is not important, just know that one suit is always
different from
the rest. Trump is the best suit, valued higher than the other three
suits
(which are basically equal). In the Trump suit, the card order changes.

The first oddity of Trump is that the Jack of the selected suit becomes
the
Right Bower, the highest ranked Trump card. The second oddity is that
the other
Jack of the same color (Diamonds and Hearts are red while Clubs and
Spades are
black) becomes the Left Bower, the second highest Trump card. This card
is
considered to be of the Trump suit for the rest of the hand. For
example, if
Spades is selected as Trump, the order of Spades becomes (lowest to
highest):
9s, Ts, Qs, Ks, As, Jc, and Js. All other suits run Nine to Ace, save
that
Clubs will be short a Jack.

The three non-Trump suits are equal, but it is good interface to sort
the by
suit alternating red, black, red, and black, I think. Especially with a
GUI,
this makes it easier to understand the hand.

Input (on STDIN) will be a line containing the Trump suit, followed by
five
lines containing a Euchre hand. For example:

Diamonds
Kc
Jh
Kd
Td
Ah

Your script should output (to STDOUT) the Trump suit, followed by the
cards in
sorted order (highest card first):

Diamonds
Jh
Kd
Td
Kc
Ah

Here’s a script that will feed your program random hands:

#!/usr/local/bin/ruby -w

build a Euchre deck

cards = Array.new
%w{9 T J Q K A}.each do |face|
%w{d c s h}.each do |suit|
cards << face + suit
end
end

choose trump

puts %w{Diamonds Clubs Spades Hearts}[rand(4)]

deal a hand

cards = cards.sort_by { rand }
puts cards[0…4]

One last thought: If accuracy is our ultimate goal here, how will you
know your
output is correct?

james · November 19, 2005, 8:32pm

On 18/11/05, Ruby Q. [email protected] wrote:

Spades is selected as Trump, the order of Spades becomes (lowest to highest):
Diamonds
Jh
cards = Array.new
cards = cards.sort_by { rand }
puts cards[0…4]

One last thought: If accuracy is our ultimate goal here, how will you know your
output is correct?

Hello James,

I have to admit that I do not totally understand. Why is in the
example the King of Clubs higher than the Ace of hearts. I thought an
Ace would be higher than a King and Clubs and Hearts are equal except
for the Jack if the trump is Diamond.

And secondly I do not understand the paragraph about the red-black sort
order.

cheers,

Brian

http://ruby.brian-schroeder.de/

Stringed instrument chords: http://chordlist.brian-schroeder.de/

james · November 19, 2005, 8:50pm

On Nov 19, 2005, at 1:31 PM, Brian Schröder wrote:

Your script should output (to STDOUT) the Trump suit, followed by
the cards in
sorted order (highest card first):
    Diamonds
    Jh
    Kd
    Td
    Kc
    Ah

Hello James,

Hello Brian.

I have to admit that I do not totally understand.

That’s probably just my terrible explination. Let’s see if I can
clear it up…

Why is in the example the King of Clubs higher than the Ace of hearts.

Cards are sorted first buy suit, then by value. Trump is a better
suit then the rest, but the others are equal and can come in any
order. The suit order above is Diamonds (Trump), Clubs, then
Hearts. Inside those suits, cards are sorted by face value.

And secondly I do not understand the paragraph about the red-black
sort order.

Technically, this is another (correct) answer to the above:

Diamonds
Jh
Kd
Td
Ah
Kc

The cards are still sorted in order of value. However, now we have
put the red suits together. I think it’s better to break them up,
when we can. That’s why my example shows Clubs between the two suits.

Does that help?

James Edward G. II

james · November 19, 2005, 8:58pm

On 19/11/05, James Edward G. II [email protected] wrote:

    Kc
Why is in the example the King of Clubs higher than the Ace of hearts.

Cards are sorted first buy suit, then by value. Trump is a better
suit then the rest, but the others are equal and can come in any
order. The suit order above is Diamonds (Trump), Clubs, then
Hearts. Inside those suits, cards are sorted by face value.

Now I understand. I always sort my cards first by value then by suite.
That was the problem.

cheers,

Brian

[snip]

Does that help?

Yes

James Edward G. II

–
http://ruby.brian-schroeder.de/

Stringed instrument chords: http://chordlist.brian-schroeder.de/

james · November 20, 2005, 4:20pm

On 11/18/05, Ruby Q. [email protected] wrote:

The card game of Euchre has an unusual ordering of cards in the hand. This
week’s Ruby Q. is to take a random Euchre hand and sort it.

Hmm. My original solution was to assign integer values to each card
and suit, and sort_by that mapping.

#!/usr/bin/ruby -w

NUMS = %w(9 T J Q K A)
SUITS = %w(h c d s)
COLOURS = Hash[*%w(s B d R c B h R)]

def card_value(card, trump)
num, suit = card.split(‘’)

value = NUMS.index(num)
value += 10 * SUITS.index(suit)
if num == 'J'
	value += 150 if COLOURS[suit] == COLOURS[trump]
	value += 10 if suit == trump
elsif suit == trump
	value += 100
end

return value

end

trump = gets.chomp
tsuit = trump[0,1].downcase

puts trump
puts $stdin.readlines.sort_by { |card| -card_value(card,tsuit) }

When I started to think about it though, that seemed a little silly to
me. If you ever use more than ten numbers, or more than 5 cards,
things start to get messy and sneaky bugs pop up. I realised that what
I was really doing was creating an array of base-10 numbers to
represent the cards. Why not just create an actual array and be done
with it?

So, here’s my version 2:

#!/usr/bin/ruby -w

NUMS = %w(9 T J Q K A)
SUITS = %w(h c d s)
COLOURS = Hash[*%w(s B d R c B h R)]

def card_value(card, trump)
num, suit = card.split(‘’)

value = Array.new

value << (num == 'J' && value[3] == 1 ? 1 : 0)
value << (num == 'J' && COLOURS[suit] == COLOURS[trump] ? 1 : 0)
value << (suit == trump ? 1 : 0)
value << SUITS.index(suit)
value << NUMS.index(num)

end

trump = gets.chomp
tsuit = trump[0,1].downcase

puts trump
puts $stdin.readlines.sort_by { |card| card_value(card,tsuit) }.reverse

Though, incidentally, I’m not sure how the performance of the two
would compare. I also wish I could think of a neater way to include
those boolean values than the ? 1 : 0 thing. I considered defining <=>
for TrueClass and FalseClass, but thought that might be a little icky.

Sam

james · November 21, 2005, 3:29am

I seriously debated with myself whether it was worth submitting my
solution. It takes a whole 100 lines of code! I decided in the end that
I would post it anyway.

I made the opposite decision to Robin S. and decided to stick with
the <=> approach. The cards do have to know about the trump suit, but
the deck class automatically handles that.

Here it is:

class Card
@@values = {‘A’ => :ace, ‘K’ => :king, ‘Q’ => :queen, ‘J’ => :jack,
‘T’ => :ten, ‘9’ => :nine}
@@value_values = {:ace => 6, :king => 5, :queen => 4, :jack => 3, :ten
=> 2, :nine => 1}
@@suits = {‘h’ => :hearts, ‘d’ => :diamonds, ‘c’ => :clubs, ‘s’ =>
:spades}
@@suit_values = {:hearts => 2, :diamonds => -2, :clubs => 1, :spades
=> -1}

# The suit_values is used to compactly calculate the order suits

should be sorted in

def initialize(string = "Jh", trump = :hearts)
	@suit = :hearts
	@value = :ace
	@trump = trump
	if string
		self.parse(string)
	end
end

def parse(string)
	cardarray = string.upcase.scan(/[AKQJT9][HDCS]/)
	if cardarray.length > 0
		@value = @@values[cardarray[0][0,1]]
		@suit = @@suits[(cardarray[0][1,1]).downcase]
	end
end

def rank_value
	case @suit
		when @trump
			return @value == :jack ? 40 : (@@value_values[@value] + 30)
		when @@suit_values.index(@@suit_values[@trump] * -1)
		# True when card is of the trump's suit's colour companion
			return @value == :jack ? 39 : (@@value_values[@value] + 10)
		when @@suit_values.index((@@suit_values[@trump] % 2) + 1)
		# Triggers for clubs if trump is red or hearts if trump is black
			return @@value_values[@value] + 20
		else
		# The last remaining suit comes last
			return @@value_values[@value]
	end
end

def <=>(other)
	self.rank_value <=> other.rank_value
end

def printable
	@@values.index(@value) + @@suits.index(@suit)
end

include Comparable

attr_accessor :trump, :value, :suit

end

class Hand
def initialize(trump = :hearts, *cards)
@cards = Array.new
@trump = trump
cards.each do |cs|
@cards << Card.new(cs, trump)
end
@cards.sort!
end

def add_card(card)
	@cards << Card.new(card, @trump)
end

def display
	@cards.sort!
	@cards.reverse.each do |card|
		puts card.printable
	end
end

def inspect
	handstring = String.new
	@cards.each do |card|
		handstring << card.printable << ', '
	end
	handstring.chop!
	handstring.chop!
end

def trump=(newtrump)
	@trump = newtrump
	@cards.each {|c| c.trump = newtrump}
end

attr_accessor :cards
attr_reader :trump

end

if FILE == $0

until (trumpline = readline()) != ""
end

case trumpline.downcase[0,1]
	when 'h'
		trump = :hearts
	when 'd'
		trump = :diamonds
	when 'c'
		trump = :clubs
	when 's'
		trump = :spades
	else
		raise StandardError, "Bad Input"
end

h = Hand.new(trump)

5.times do |t|
	cardline = readline()
	h.add_card(cardline)
end

puts trump.to_s.capitalize
h.display

end