unzip function?

[Hrvoje Niksic]

Neal Becker <ndbecker2 at gmail.com> writes:

> python has builtin zip, but not unzip
>
> A bit of googling found my answer for my decorate/sort/undecorate problem:
>
> a, b = zip (*sorted ((c,d) for c,d in zip (x,y)))
>
> That zip (*sorted...
>
> does the unzipping.
>
> But it's less than intuitively obvious.
>
> I'm thinking unzip should be a builtin function, to match zip.

"zip" and "unzip" are one and the same since zip is inverse to itself:

>>> [(1, 2, 3), (4, 5, 6)]
[(1, 2, 3), (4, 5, 6)]
>>> zip(*_)
[(1, 4), (2, 5), (3, 6)]
>>> zip(*_)
[(1, 2, 3), (4, 5, 6)]
>>> zip(*_)
[(1, 4), (2, 5), (3, 6)]

What you seem to call unzip is simply zip with a different signature,
taking a single argument:

>>> def unzip(x):
...   return zip(*x)
...
>>> [(1, 2, 3), (4, 5, 6)]
[(1, 2, 3), (4, 5, 6)]
>>> unzip(_)
[(1, 4), (2, 5), (3, 6)]
>>> unzip(_)
[(1, 2, 3), (4, 5, 6)]
>>> unzip(_)
[(1, 4), (2, 5), (3, 6)]