list - Trying to find all combinations of a 2-state vector (in python) -

i trying find combinations of 4 element vector contains 1's , -1's. ex (1,1,1,1),(-1,1,1,1),...(-1,-1,-1,-1) etc idea pretty inefficient im sure can't think of way it, here trying do. found how many total vectors there be, created many empty lists. began vector a , compared each list in vectors. if a matched of lists randomly changed sign of element of a, , again checked new list a against vectors. if a didn't find match replaced on of lists in vectors, , while loop incremented 1. should proceed until possible combinations have been found , printed. code spitting out first change in vectors continually looping without adding new a's vectors. can spot in code isn't doing intended and/or point me in right direction? thanks

import random numvec = 2**4 # number of macrostates 4 component 2-state system  vectors = [[0,0,0,0] in range(numvec)] #initializing numvec vectors  = [1,1,1,1] = 0 while < 16:     if any(x == x in vectors):         y = random.randrange(0, 3)         a[y] = a[y] * -1     else:         vectors[i] =         print vectors[i]          += 1  print vectors 

oh , again realize method incredibly inefficient homework assignment more concerned being able python want do, using bunch of built in functions work me. again.

vectors[i] = 

this doesn't create copy of a. when change a, contents of vectors change, because vectors[0] , a same object after first time line runs. fix this, make new a object every time, or copy a , insert copy list.

if want make copy, can use python's slice notation:

vectors[i] = a[:]