A really bad idea.

[Chad Netzer]

On Thursday 14 November 2002 20:49, Paul Foley wrote:
> On Thu, 14 Nov 2002 15:33:33 -0800, Russell E Owen wrote:
> > On the other hand, I like zip just fine (though I lament the lack of an
> > unzip counterpart).
>
> Eh?  Zip is its own inverse!

Hmmm...

Python 2.2.2 (#4, Oct 15 2002, 04:21:28) 
>>> a = [1,2,3]
>>> b = ['a','b', 'c']

>>> zip(a,b)
[(1, 'a'), (2, 'b'), (3, 'c')]

>>> zip(zip(a,b))
[((1, 'a'),), ((2, 'b'),), ((3, 'c'),)]

>>> c,d = zip(zip(a,b))
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
ValueError: unpack list of wrong size

So, not quite.

But, after some thought, I see that you mean this (which is cool):

>>> c,d = zip(*zip(a,b))
>>> c
(1, 2, 3)
>>> d
('a', 'b', 'c')

ie. it's its own inverse, if you consider some extra syntax (and getting 
tuples, not lists).

-- 
Bay Area Python Interest Group - http://www.baypiggies.net/

Chad Netzer
cnetzer at mail.arc.nasa.gov