swapping numeric items in a list

[Simon Forman]

Jiang Nutao wrote:
> Hi,
>
> I simplify my problem like below
>
> To convert list
>     aa = [0x12, 0x34, 0x56, 0x78]
> into
>     [0x34, 0x12, 0x78, 0x56]
>
> How to do it fast? My real list is huge.
>
> Thanks a lot.
> Jason

Here's simple and probably fast enough way (but it won't work right on
odd length lists):

def rev(n):
    i = iter(n)
    while True:
        a = i.next()
        yield i.next()
        yield a


Example of use:

r = range(24)

print list(rev(r))

If your list comes from binary (str) data, and you're dealing with
endianness, I smell a faster way using struct.

Peace,
~Simon