在txt文件中打印2D数组只保存最后一行-错误地使用.join？

# 2D数组示例
array_2d = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

# 将每一行转化为字符串并使用.join方法连接起来
result = '\n'.join([' '.join(map(str, row)) for row in array_2d])

# 将结果写入txt文件
with open('output.txt', 'w') as f:
    f.write(result)

# 2D数组示例
array_2d = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

# 获取最后一行的字符串
last_row = ' '.join(map(str, array_2d[-1]))

# 将最后一行写入txt文件
with open('output.txt', 'w') as f:
    f.write(last_row)