[Python-ideas] Reduce/fold and scan with generator expressions and comprehensions

[David Mertz]

Consuming the iterator is *necessary* to get the last item. There's no way
around that.

Obviously, you could itertools.tee() it first if you don't mind the cache
space. But there cannot be a generic "jump to the end" of an iterator
without being destructive.

On Oct 23, 2016 8:43 AM, "Steven D'Aprano" <steve at pearwood.info> wrote:

> On Sun, Oct 23, 2016 at 08:37:07AM -0700, David Mertz wrote:
> > Of course. But if you want last(), why not just spell the utility
> function
> > as I did? I.e. as a function:
> >
> >     def last(it):
> >          for item in it:
> >              pass
> >         return item
> >
> > That works fine for any iteratable (including a list, array, etc),
> whether
> > or not it's a reduction/accumulation.
>
> That's no good, because it consumes the iterator. Yes, you get
> the last value, but you actually needed to do work on all the
> previous values too.
>
>
> --
> Steve
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