On Wed, 28 Mar 2007 18:16:31 -0700, s99999999s2003 wrote: > what do you mean by create new object when using list comprehensoin or > list()? Does using slicing create a new object as well?
Yes it does. >>> alist = [1, 2, 4, 8, 16] >>> blist = alist # not a copy >>> id(alist) == id(blist) True >>> blist = alist[:] # a copy >>> id(alist) == id(blist) False By the way, "id(obj) == id(another_object)" is just a long way of writing "obj is another_object". In general: - use a list comprehension when you need to calculate the list items - use slicing when you are copying an actual list, or if you don't care what type of object you get - use the list() function when your existing object might not be an actual list, and you want the copy to be a list. E.g. atuple = (1, 2, 3) alist = [2*n+3 for n in atuple] btuple = atuple[:] blist = list(atuple) -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
