Shift list elements to the right and shift list element at the end to the beginning

Question

I want to rotate elements in a list, e.g. - shift the list elements to the right so ['a','b','c','d'] would become ['d','a','b','c'], or [1,2,3] becomes [3,1,2].

I tried the following, but it's not working:

def shift(aList):
    n = len(aList)
    for i in range(len(aList)):
        if aList[i] != aList[n-1]:
            aList[i] = aList[i+1]
             return aList
         elif aList[i] == aList[i-1]:
            aList[i] = aList[0]
            return aList
shift(aList=[1,2,3])

Answer 1

If you are allergic to slice notation: a.insert(0,a.pop())

Usage:

In [15]: z=[1,2,3]

In [16]: z.insert(0,z.pop())

In [17]: z
Out[17]: [3, 1, 2]

In [18]: z.insert(0,z.pop())

In [19]: z
Out[19]: [2, 3, 1]

Answer 2

You can use this:

li=li[-1:]+li[:-1]

Answer 3

You can use negative indices together with list concatenation:

def shift(seq, n=0):
    a = n % len(seq)
    return seq[-a:] + seq[:-a]

Answer 4

If you are trying to shift the elements, use collections.deque rotate method:

#! /usr/bin/python3

from collections import deque
a = deque([1, 2, 3, 4])
a.rotate()
print(a)

Result:

[2, 3, 4, 1]

Answer 5

You can just slice the last element off the list, then add it to the beginning of a new list:

aList = [aList[-1]] + aList[:-1]

Here is the result:

>>> aList = [1,2,3]
>>> aList = [aList[-1]] + aList[:-1]
>>> aList
[3, 1, 2]