修改2D python列表中的一些元素

Question

My list looks like this:

board = [ [ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0] ]

How can I modify some of the elements? Eg: the first element in each row = 0. I want to replace them with fives. So my list would look like this:

board = [ [ 5 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 5 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 5 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 5 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 5 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 5 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 5 , 0 , 0 , 0 , 0 , 0 , 0 , 0],
      [ 5 , 0 , 0 , 0 , 0 , 0 , 0 , 0] ]

Answer 1

You can access a specific cell of a 2D array by doing board[r][c] , where r is the row and c is the column. For replacing the first column with 5's, you could do:

for row in board:
    row[0] = 5

This iterates over every row in board , and sets the first item in each row to 0.