Card shuffles: Difference between revisions

=={{header|Python}}==

{{trans|D}}

<lang python>import random

def riffleShuffle(va, flips):

nl = va

for n in range(flips):

#cut the deck at the middle +/- 10%, remove the second line of the formula for perfect cutting

cutPoint = len(nl)/2 + random.choice([-1, 1]) * random.randint(0, len(va)/10)

# split the deck

left = nl[0:cutPoint]

right = nl[cutPoint:]

del nl[:]

while (len(left) > 0 and len(right) > 0):

#allow for imperfect riffling so that more than one card can come form the same side in a row

#biased towards the side with more cards

#remove the if and else and brackets for perfect riffling

if (random.uniform(0, 1) >= len(left) / len(right) / 2):

nl.append(right.pop(0))

else:

nl.append(left.pop(0))

if (len(left) > 0):

nl = nl + left

if (len(right) > 0):

nl = nl + right

return nl

def overhandShuffle(va, passes):

mainHand = va

for n in range(passes):

otherHand = []

while (len(mainHand) > 0):

#cut at up to 20% of the way through the deck

cutSize = random.randint(0, len(va) / 5) + 1

temp = []

#grab the next cut up to the end of the cards left in the main hand

i=0

while (i<cutSize and len(mainHand) > 0):

temp.append(mainHand.pop(0))

i = i + 1

#add them to the cards in the other hand, sometimes to the front sometimes to the back

if (random.uniform(0, 1) >= 0.1):

#front most of the time

otherHand = temp + otherHand

else:

otherHand = otherHand + temp

#move the cards back to the main hand

mainHand = otherHand

return mainHand

print "Riffle shuffle"

nums = [x+1 for x in range(21)]

print nums

print riffleShuffle(nums, 10)

print

print "Riffle shuffle"

nums = [x+1 for x in range(21)]

print nums

print riffleShuffle(nums, 1)

print

print "Overhand shuffle"

nums = [x+1 for x in range(21)]

print nums

print overhandShuffle(nums, 10)

print

print "Overhand shuffle"

nums = [x+1 for x in range(21)]

print nums

print overhandShuffle(nums, 1)

print

print "Library shuffle"

nums = [x+1 for x in range(21)]

print nums

random.shuffle(nums)

print nums

print</lang>

{{out}}

<pre>Riffle shuffle

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21]

[4, 16, 5, 19, 3, 14, 2, 9, 20, 13, 17, 10, 6, 7, 1, 18, 12, 11, 8, 21, 15]

Riffle shuffle

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21]

[13, 14, 15, 1, 16, 2, 3, 17, 4, 5, 18, 6, 7, 19, 8, 9, 20, 10, 11, 21, 12]

Overhand shuffle

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21]

[21, 12, 5, 16, 7, 2, 15, 14, 20, 6, 8, 11, 13, 1, 4, 17, 19, 9, 3, 18, 10]

Overhand shuffle

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21]

[21, 20, 19, 18, 16, 17, 14, 15, 11, 12, 13, 4, 5, 6, 7, 1, 2, 3, 8, 9, 10]

Library shuffle

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21]

[14, 12, 2, 17, 18, 21, 8, 4, 15, 9, 11, 10, 3, 1, 7, 19, 20, 6, 5, 16, 13]</pre>