On Dec 4, 7:00 am, Edvin Fuglebakk <[EMAIL PROTECTED]> wrote: ... > def orderedCombinations(pool, k): > """ > Generator yielding ordered selections of size k with repetition from > pool. > """ > > if k == 1: > for m in pool: > yield [m] > > if k > 1: > > for m in pool: > for combo in orderedCombinations(pool, k-1): > > #insert and pop to avoid copying entire list > combo.insert(0,m) > yield combo > combo.pop(0)
'combo.pop' is the problem. When the caller saves the iteration variable, the generator modifies it on the next call. >>> a= [] >>> b= [0] >>> a.append( b ) >>> a [[0]] >>> b.insert( 0, 1 ) >>> a [[1, 0]] If you want your output to have X lists, you need to create X lists. Perhaps copy is not the most efficient, but you can't have one list try do be X different lists when viewed from different angles. Though that would be cool. -- http://mail.python.org/mailman/listinfo/python-list
