python - 创建列表列表。修改列表中的元素

Question

要求:

定义函数createMatDimXDim(dim)该函数接收大于或等于2的正整数，返回维度为dim x dim的方阵，其中内容为行号乘以10加上列号的数字。

预期输出:

print (createMatDimXDim (4)) 
[[0, 1, 2, 3], [10, 11, 12, 13], [20, 21, 22, 23], [30, 31, 32, 33]]

我的代码:

def createMatDimXDim (dim):
    lis=[[0] for i in range(dim)]
    for i in range(dim):
        lis[i][0]=i*10
        for i in range(dim):
           lis[i].append(int(lis[i][0])+1)
    return lis

我的代码输出:

[[0, 1, 1, 1, 1], [10, 1, 11, 11, 11], [20, 1, 1, 21, 21], [30, 1, 1, 1, 31]]

我想这样做:

lis[i].append(int(lis[i][i-1])+1)

但它给了我一个IndexError。

Answer 1

def createMatDimXDim (dim):
    lis=[[0] for i in range(dim)]
    for i in range(dim):
        lis[i][0]=i*10
        for j in range(dim-1):               # for the nested loop you need to use a new 
                                             # variable j
           lis[i].append(int(lis[i][j])+1)
    return lis

createMatDimXDim(4)
# [[0, 1, 2, 3], [10, 11, 12, 13], [20, 21, 22, 23], [30, 31, 32, 33]]

列表理解的另一个选项:

dim = 4
[[i * 10 + j for j in range(dim)] for i in range(dim)]
# [[0, 1, 2, 3], [10, 11, 12, 13], [20, 21, 22, 23], [30, 31, 32, 33]]