On Fri, May 30, 2014 at 9:38 PM, Josh English <joshua.r.engl...@gmail.com> wrote: > I am trying to whip up a quick matrix class that can handle multiplication. > > Should be no problem, except when it fails. > > [SNIP] > > def zero_matrix(rows, cols): > row = [0] * cols > data = [] > for r in range(rows): > data.append(row)
Each row of the matrix that you create here is the *same* list, not different lists that happen to be equal. So when you mutate one row, you mutate all of them. See: https://docs.python.org/3/faq/programming.html#how-do-i-create-a-multidimensional-list -- https://mail.python.org/mailman/listinfo/python-list
