[Tutor] rotating a list

[Danny Yoo]

> PS. If my man Danny is out there... 'Hi'

Hey Kevin, it's been a long time!

Looks like you've gotten a few responses to the list-rotation question, so
I'd better not regurgitate them too much.  *grin*


But just out of curiosity, is it necessary that we do have to account for
rotating the list of length one or zero?

If so, Gregor's solution:

###
def rotate(x):
    x[:-1],x[-1] = x[1:],x[0]
###

will need an amendment to make it work on empty lists, or else we may run
into an IndexError:

###
>>> L = []
>>> rotate(L)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "<stdin>", line 2, in rotate
IndexError: list index out of range
###


One way we can fix the definition is to redefine it so that it always does
list slicing on its input:

###
>>> def rotate(L):
...     """Mutates list L and rotates all the elements to the left."""
...     x[:-1], x[-1:] = x[1:], x[:1]
...
###

The symmetry in the definition here appeals to me.  *grin*


Talk to you later!