How to slice a circular list

Question

Suppose I have list as follow:

lst = [0,10,20,30,40,50,60,70]

I want elements from lst from index = 5 to index = 2 in cyclic order.

lst[5:2] yields [] I want lst[5:2] = [50,60,70,0,10]. Is there any simple library function to do this?

Answer 1

Simply split the slicing in two if the second term is smaller than the first:

lst = [0,10,20,30,40,50,60,70]


def circslice(l, a, b):
    if b>=a:
        return l[a:b]
    else:
        return l[a:]+l[:b]
    
circslice(lst, 5, 2)

output: [50, 60, 70, 0, 10]