Question

我需要能够将列表中的每秒数乘以2，所以说：

List = [1,2,3,4]

我希望这会返回[1,4,3,8]但是我尝试过的所有方法，例如

credit_card = [int(x) for x in input().split()]

credit_card[::2] = [x*2 for x in credit_card[::2]]

print(credit_card)

如果我在返回[2,2,6,4]

之前输入相同的列表

有没有办法完成我想要完成的任务？

Answer 1

你几乎就在那里，你只需要从第二个（1索引）元素开始：

credit_card[1::2] = [x*2 for x in credit_card[1::2]]

也就是说，由于您似乎正在实施Lunh checksum，因此您只需要这些数字的总和，而无需更新原始数据，例如在this example中完成。

Answer 2

lst = [1,2,3,4]

new_lst = [2*n if i%2 else n for i,n in enumerate(lst)]     # => [1, 4, 3, 8]

Answer 3

credit_card = input().split()
for x in len(credit_card)
    if x % 2 != 0
        credit_card[x] = credit_card[x] * 2

print (credit_card)

Answer 4

另一种使用枚举的解决方案：

SELECT patfile.Chart_Number
    ,patfile.employer AS e_name
FROM patfile;

IF (
        patfile.employer = ''
        ,(
            SELECT addfile.NAME AS e_name
            FROM addfile
            WHERE patfile.employer = addfile.code
            )
        ,''
        ) ELSE patfile.employer AS e_name endif

其中 i 是 l 的 p 元素。

Answer 5

for i,_ in enumerate(credit_card):
    if i%2:
        credit_card[i] *= 2

或者如果你想要幻想：

 credit_card=[credit_card[i]*(2**(i%2)) for i in range(len(credit_card))]

Answer 6

>>> l = [1,2,3,4]
>>> 
>>> list(map(lambda x: x*2 if l.index(x)%2 else x, l))
[1, 4, 3, 8]

将每秒的数字乘以列表

6 个答案: