按列排列的前n个元素

# 假设你有一个二维列表，表示一个矩阵
matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

n = 2  # 获取每列的前两个元素

result = [col[:n] for col in zip(*matrix)]
print(result)

[(1, 4), (2, 5), (3, 6)]