Python：有没有办法从一个特定的索引循环遍历一个列表，然后再回到前面？

Question

Is there a way to loop through a list from a specific index that wraps back to the front?

let's imagine a list

arr = [0,1,2,3,4,5,6,7,8,9]

is there a way to loop from 4 onwards, wrapping back to the front and continuing from there?

expected output

4 5 6 7 8 9 0 1 2 3

Visualized example

Answer 1

There is. You can slice the list in two and iterate over them in the same loop like this:

arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
idx = 4
for i in arr[idx:] + arr[:idx]:
    print(i)

Answer 2

If you want to use the iterator directly, then you can use

[x for x in arr[4:] + arr[:4]]

Otherwise if you use indices:

[arr[(4 + i)%len(arr)] for i in range(len(arr))]

The examples produce a new list, but the idea is here