Initialization and assignment of Python two-dimensional list array list

Reference Code

List=[]
Length=8
for i in range(Length):
    List.append([])#初始化二维列表
List[0].append(1)
List[0].append(2)
List[0].append(3)
List[7].append(50)
print(List)

operation result

[[1, 2, 3], [], [], [], [], [], [], [50]]