Card shuffling

fisher_yates_shuffle.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
from random import randrange
 
def fisher_yates_shuffle(unshuffled, shuffled):
    """
    http://en.wikipedia.org/wiki/Fisher-Yates_shuffle#The_modern_algorithm
    ...but using recursion instead of counters
    """
    if not unshuffled: return shuffled
    randi = randrange(0, len(unshuffled))
    # the challenge would be to support tuples...
    unshuffled[0], unshuffled[randi] = unshuffled[randi], unshuffled[0]
    return fisher_yates_shuffle(unshuffled[1:], shuffled + [unshuffled[0]])

def sort_shuffle(cards):
    """
    http://en.wikipedia.org/wiki/Fisher-Yates_shuffle#Comparison_with_other_shuffling_algorithms
    Same again but sort use a random list of weights...
    (returns a tuple not a list)
    """
    weights = range(len(cards))
    random_weights = []
    while weights:
        random_weights.append(weights.pop(randrange(0, len(weights))))
    return zip(*sorted(zip(random_weights, cards)))[1]
 
if __name__ == '__main__':
    cards = range(52)  
    print fisher_yates_shuffle(cards, [])
    print sort_shuffle(cards)