python - permutations with unique values -

itertools.permutations generates elements treated unique based on position, not on value. want avoid duplicates this:

>>> list(itertools.permutations([1, 1, 1])) [(1, 1, 1), (1, 1, 1), (1, 1, 1), (1, 1, 1), (1, 1, 1), (1, 1, 1)] 

filtering afterwards not possible because amount of permutations large in case.

does know of suitable algorithm this?

thank much!

edit:

what want following:

x = itertools.product((0, 1, 'x'), repeat=x) x = sorted(x, key=functools.partial(count_elements, elem='x')) 

which not possible because sorted creates list , output of itertools.product large.

sorry, should have described actual problem.

class unique_element:     def __init__(self,value,occurrences):         self.value = value         self.occurrences = occurrences  def perm_unique(elements):     eset=set(elements)     listunique = [unique_element(i,elements.count(i)) in eset]     u=len(elements)     return perm_unique_helper(listunique,[0]*u,u-1)  def perm_unique_helper(listunique,result_list,d):     if d < 0:         yield tuple(result_list)     else:         in listunique:             if i.occurrences > 0:                 result_list[d]=i.value                 i.occurrences-=1                 g in  perm_unique_helper(listunique,result_list,d-1):                     yield g                 i.occurrences+=1     = list(perm_unique([1,1,2])) print(a) 

result:

[(2, 1, 1), (1, 2, 1), (1, 1, 2)] 

edit (how works):

i rewrite upper program longer more readable have hard time explain how works, let me try. in order understand how works have understand similar, simpler program yield permutations repetition.

def permutations_with_replecement(elements,n):     return permutations_helper(elements,[0]*n,n-1)#this generator  def permutations_helper(elements,result_list,d):     if d<0:         yield tuple(result_list)     else:         in elements:             result_list[d]=i             all_permutations = permutations_helper(elements,result_list,d-1)#this generator             g in all_permutations:                 yield g 

this program in simpler. d stands depth in permutations_helper , has 2 functions. 1 function stopping condition of our recursive algorithm , other result list, passed around.

instead of returning each result yield it. if there no function/operator yield had push result in queue @ point of stopping condition. way once stopping condition meet result propagated trough stack caller. purpouse of
for g in perm_unique_helper(listunique,result_list,d-1): yield g each result propagated caller.

back original program: have list of unique elements. before can use each element, have check how many of them still available push on result_list. working of program similar compared permutations_with_replecement difference each element can not repeated more times in perm_unique_helper.