Permutation

def permute(list):
    if not list:
        return [list]
    else:
        res = []
        for i in range(len(list)):
            rest = list[:i] + list[i+1:]
            for x in permute(rest):
                res.append(list[i:i+1]+x)
        return res
 
print permute(['a','b','c','d','e'])

def subset(list, size):
    if size == 0 or not list:
        return [list[:0]]
    else:
        result =[]
        for i in range(len(list)):
            pick = list[i:i+1]
            rest = list[:i] + list[i+1:]
            for x in subset(rest, size-1):
                result.append(pick+x)
        return result
 
print subset([1,2,3,4,5,6,7,8,9], 4)

from __future__ import generators
 
def xcombinations(items, n):
    if n==0: yield []
    else:
        for i in xrange(len(items)):
            for cc in xcombinations(items[:i]+items[i+1:],n-1):
                yield [items[i]]+cc
 
def xuniqueCombinations(items, n):
    if n==0: yield []
    else:
        for i in xrange(len(items)):
            for cc in xuniqueCombinations(items[i+1:],n-1):
                yield [items[i]]+cc
            
def xselections(items, n):
    if n==0: yield []
    else:
        for i in xrange(len(items)):
            for ss in xselections(items, n-1):
                yield [items[i]]+ss
 
def xpermutations(items):
    return xcombinations(items, len(items))
 
if __name__=="__main__":
    print "Permutations of 'love'"
    for p in xpermutations(['l','o','v','e']): print ''.join(p)
 
    print
    print "Combinations of 2 letters from 'love'"
    for c in xcombinations(['l','o','v','e'],2): print ''.join(c)
 
    print
    print "Unique Combinations of 2 letters from 'love'"
    for uc in xuniqueCombinations(['l','o','v','e'],2): print ''.join(uc)
 
    print
    print "Selections of 2 letters from 'love'"
    for s in xselections(['l','o','v','e'],2): print ''.join(s)
 
    print
    print map(''.join, list(xpermutations('done')))

출처 : http://biohackers.net/wiki/Permutation