为每个文本文件行创建多个3x3网格python 3

with open('filename.txt', 'r') as file:
    lines = file.readlines()

for line in lines:
    grid = [['-' for _ in range(3)] for _ in range(3)]
    for i in range(len(line)):
        row = i // 3
        col = i % 3
        grid[row][col] = line[i]
    for row in grid:
        print(' '.join(row))
    print()