On 09/10/2007, Chuk Goodin <[EMAIL PROTECTED]> wrote: > I've got a bit of code here that's giving me some trouble. I am trying > to make a 2 dimensional array with nested lists, but when I try to > change one element, it changes all the elements in that "column". > > I'm trying to get it to make only one 'X'. Any hints? it feels kind of > like a syntax error on my part...
Nah, it's more subtle than that. This is your problem here: > board = [['.']*width]*depth Let's break this up a bit: row = ['.']*width board = [row]*depth This gives you a list that looks like this: [row, row, row, row, row, row, row] You see that? Every interior list is the _same list_. So when you change one, you change them all (because there is only one there to change). You need to make a new list for each row. You could do that in a loop: board = [] for i in range(depth): board.append(['.']*width) or, more compactly, in a list comprehension: board = [['.']*width for i in range(depth)] BTW, when you write ['.']*width, that gives you a list with `width` copies of the same string. But it doesn't matter because strings are immutable. HTH! -- John. _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
