# Card shuffling techniques # Created by Christof Becu on 26/12/17 14:32 # Last modified on 28/12/17 15:46 def initialize_deck values = ["A", 2, 3, 4, 5, 6, 7, 8, 9, 10, "J", "Q", "K" ] suits = [ "Hearts", "Spades", "Clubs", "Diamonds" ] deck = suits.product(values) (0..deck.size-1).each {|x| deck[x] = deck[x].join(' ')} return deck end def show(deck) (0..12).each {|x| print "| #{deck[x].center(12)} | #{deck[x+13].center(12)} | #{deck[x+26].center(12)} | #{deck[x+39].center(12)} |\n" } end def in_riffle_shuffle(deck) #or dovetail shuffle or leafing the cards. a recommendation that card decks be riffled seven times in order to randomize them thoroughly. first_pile = deck.slice(0, 26) second_pile = deck.slice(26, 51) deck.clear while first_pile.size > 0 || second_pile.size > 0 choose_pile = rand(2) case choose_pile when 0 if first_pile.size > 0 deck << first_pile.shift end when 1 if second_pile.size > 0 deck << second_pile.shift end end end return deck end def perfect_riffle_shuffle(deck, in_out=true) #There are two types of perfect riffle shuffles: if the top card moves to be second from the top then it is an in shuffle, #otherwise it is known as an out shuffle (which preserves both the top and bottom cards). first_half = deck.slice(0, 26) second_half = deck.slice(26, 51) deck.clear (0..25).each {|x| if in_out == true deck << second_half[x] deck << first_half[x] else deck << first_half[x] deck << second_half[x] end } return deck end def corgi_shuffle(deck) #simply spreading the cards out face down, and sliding them around and over each other this needs work because shuffle is not the way deck.shuffle end def pile_shuffle(deck) #Cards are simply dealt out into a number of piles, then the piles are stacked on top of each other pile_1, pile_2, pile_3, pile_4, pile_5, pile_6, pile_7, pile_8 = [], [], [], [], [], [], [], [] while deck.size > 0 pile_1 << deck.shift if deck.size == 0 then break end pile_2 << deck.shift if deck.size == 0 then break end pile_3 << deck.shift if deck.size == 0 then break end pile_4 << deck.shift if deck.size == 0 then break end pile_5 << deck.shift if deck.size == 0 then break end pile_6 << deck.shift if deck.size == 0 then break end pile_7 << deck.shift if deck.size == 0 then break end pile_8 << deck.shift if deck.size == 0 then break end end deck = pile_8 + pile_7 + pile_6 + pile_5 + pile_4 + pile_3 + pile_2 + pile_1 return deck end def mongean_shuffle(deck) #take the top card from the left hand and transfer it to the right, putting the second card at the top of the new deck, the third #at the bottom, the fourth at the top, the fifth at the bottom, etc. Twelve perfect Mongean shuffles restore a 52-card deck temp = Array.new (0..51).each {|x| x % 2 != 0 ? temp.unshift(deck[x]) : temp.push(deck[x]) } return temp end def mexican_spiral_shuffle(deck) #cyclic actions of moving the top card onto the table, then the new top card under the deck, #the next onto the table, next under the deck, and so on table = Array.new while deck.size > 0 table.push(deck.shift) deck.push(deck.shift) deck.compact! table.compact! end return table end def another_shuffle(deck) #places each card in random order at the bottom of the deck 51.downto(0) {|x| i = rand(0..x) deck.push(deck.delete_at(i)) } return deck end deck = initialize_deck puts "\ninitial deck\n\n" show(deck) puts "\nin riffle shuffle\n\n" show(in_riffle_shuffle(deck)) deck = initialize_deck puts "\nperfect in riffle shuffle\n\n" show(perfect_riffle_shuffle(deck, true)) deck = initialize_deck puts "\nperfect out riffle shuffle\n\n" show(perfect_riffle_shuffle(deck, false)) deck = initialize_deck puts "\ncorgi shuffle\n\n" show(corgi_shuffle(deck)) deck = initialize_deck puts "\npile shuffle\n\n" show(pile_shuffle(deck)) deck = initialize_deck puts "\nmongean shuffle\n\n" show(mongean_shuffle(deck)) deck = initialize_deck puts "\nmexican spiral shuffle\n\n" show(mexican_spiral_shuffle(deck)) deck = initialize_deck puts "\nanother shuffle\n\n" show(another_shuffle(deck))

Card Shuffling Techniques