On 5/25/07, Matt Smith <[EMAIL PROTECTED]> wrote: > def update_matrix(matrix): > matrix_updated = matrix
That line assigns the name matrix_updated to the same list-of-lists as matrix. Since lists are mutable objects, changing matrix_updated is also changing matrix. What you need is to bind matrix_updated to a new copy of matrix instead. At the top of your code add: from copy import deepcopy and replace the first line of update_matrix() with: matrix_updated = deepcopy(matrix) After making that change, your code appears to run beautifully! -- Jerry _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor