shuffling elements of a list

[Alex Martelli]

Peter Otten <__peter__ at web.de> wrote:

> Gerard Flanagan wrote:
> > Ben Finney wrote:
> 
> >>         pile_index = 0
> >>         for card in deck:
> >>             piles[pile_index].append(card)
> >>             pile_index = (pile_index + 1) % numpiles
> > 
> > no need to maintain an index ;-)
> > 
> >         piles = [ list() for _ in range(n) ]
> >         for i, card in enumerate(deck):
> >             piles[i % numpiles].append(card)
> 
> No need to maintain an index ;-)
> 
> piles = [deck[start::numpiles] for start in range(numpiles)]
> 
> Assuming deck is a list, that is.

Or, for deck hypothetically being an arbitrary iterable,

import itertools as it
piles = [ list() for _ in range(numpiles) ]
for pile, card in it.izip(it.cycle(piles), deck):
    pile.append(card)

i.e., let itertools do the cycling for you.  But, sure, for this problem
one can no doubt assume that deck is sliceable, and extended slicing
(==slicing with a stride) comes in handy.


Alex