Combined natural and unnatural list sorting

[Andrea Griffini]

On Wed, 16 Jun 2004 00:23:47 GMT, Derek Basch <dbasch at yahoo.com>
wrote:

>> > I need to sort a list using an unnatural sequence.

...

This is my first attempt, I'm new to python so may be there are
better ways to do it...

  >>> def scol(x,y):
  ...   (cx,sx) = x.split("/")
  ...   (cy,sy) = y.split("/")
  ...   if sx==sy: return cmp(cx,cy)
  ...   return cmp(xs[sx],xs[sy])
  ...
  >>> xs = dict(S=1,M=2,L=3)
  >>> a = ["White/M","White/L","White/S",
           "Orange/L","Blue/M","Purple/L"]
  >>> a.sort(scol)
  >>> a
  ['White/S', 'Blue/M', 'White/M', 'Orange/L', 'Purple/L', 'White/L']
  >>>

I can think to a probably faster way if the list is big...
just "transform" every string to a (xs[sx],cx) tuple once;
then do a regular sort, then transform back to the string form.

HTH
Andrea