[EMAIL PROTECTED] wrote: > I do not have a clue what is happening in the code below. > >>>> a=[[2,4],[9,3]] >>>> b=a >>>> [map(list.sort,b)] > [[None, None]] >>>> b > [[2, 4], [3, 9]] >>>> a > [[2, 4], [3, 9]] > > I want to make a copy of matrix a and then make changes to the > matrices separately. I assume that I am missing a fundamental > concept. Any help would be appreciated.
You are missing that the operation b=a is not a copying, but a mere name-binding. The object that a points to now is also pointed at by b. If you need copies, use the copy-module, with it's method deepcopy. Diez -- http://mail.python.org/mailman/listinfo/python-list