different ways to creating two lists from one

[Diez B. Roggisch]

> But suppose generating s0 is expensive and/or s0 is big. In otherwords I'd
> like to go over only once and I don't want to keep it around any longer
> than I have to.
> 
> I could do something like:
> 
> for a, b in [(x + x, x * x) for x in s0]:
>      s1.append(a)
>      s2.append(b)
> 
> Is there a better / cleaner way that I'm missing?

Why the uneccessary list comprehension? That makes only sense if you want to
actually keep it. Which you say you don't want :)

So simply

for x in s0:
     s1.append(2*x)
     s2.append(x*x)

should do the trick. Especially if s0 itselft is an iterator.

Diez