How to print Sudoku board using Python class?

Question

Exactly as my post title says, I'm trying to create a class to solve Sudoku game and I wanted to print a board using OOP style and if name == "main":

My output suppose to look like this:

Here's my code so far:

class Sudoku:
    def __init__(self):
        self.board = [
            [7, 8, 0, 4, 0, 0, 1, 2, 0],
            [6, 0, 0, 0, 7, 5, 0, 0, 9],
            [0, 0, 0, 6, 0, 1, 0, 7, 8],
            [0, 0, 7, 0, 4, 0, 2, 6, 0],
            [0, 0, 1, 0, 5, 0, 9, 3, 0],
            [9, 0, 4, 0, 6, 0, 0, 0, 5],
            [0, 7, 0, 3, 0, 0, 0, 1, 2],
            [1, 2, 0, 0, 0, 7, 4, 0, 0],
            [0, 4, 9, 2, 0, 6, 0, 0, 7]
        ]

    def print_board(self, board) -> None:
        for row in range(len(board)):
            if row % 3 == 0 and row != 0:
                print("- - - - - - - - - - - - - ")

        for col in range(len(board[0])):
            if col % 3 == 0 and col != 0:
                print(" | ", end="")

            if col == 8:
                print(board[row][col])
            else:
                print(str(board[row][col]) + " ", end="")

    # Not sure if we need string representation of the board
    # def __str__(self):
    #     return f"{self.board}"


if __name__ == "__main__":
    sudoku = Sudoku()
    sudoku.print_board(sudoku.board)

And here's the output that I'm getting from the above code:

Thank you in advance.

Answer 1

The problem is that the 'columns' loop isn't nested inside the 'rows' loop, your code should look something like this:

class Sudoku:
def __init__(self):
    self.board = [
        [7, 8, 0, 4, 0, 0, 1, 2, 0],
        [6, 0, 0, 0, 7, 5, 0, 0, 9],
        [0, 0, 0, 6, 0, 1, 0, 7, 8],
        [0, 0, 7, 0, 4, 0, 2, 6, 0],
        [0, 0, 1, 0, 5, 0, 9, 3, 0],
        [9, 0, 4, 0, 6, 0, 0, 0, 5],
        [0, 7, 0, 3, 0, 0, 0, 1, 2],
        [1, 2, 0, 0, 0, 7, 4, 0, 0],
        [0, 4, 9, 2, 0, 6, 0, 0, 7]
    ]

def print_board(self, board) -> None:
    for row in range(len(board)):
        if row % 3 == 0 and row != 0:
            print("- - - - - - - - - - - - - ")
        for col in range(len(board[0])):
            if col % 3 == 0 and col != 0:
                print(" | ", end="")

            if col == 8:
                print(board[row][col])
            else:
                print(str(board[row][col]) + " ", end="")

if __name__ == "__main__":
    sudoku = Sudoku()
    sudoku.print_board(sudoku.board)