lyst[:None]

[Jacek Generowicz]

Oren Tirosh <oren-py-l at hishome.net> writes:

> >     [ foo(x) for x in bar][:limit]
> 
> This makes redundant calls to foo. Everything after limit will be
> calculated and then thrown away. Try this:
> 
>      [foo(x) for x in bar:[limit]]

Doh!  Thanks for pointing that out.

"Raymond Hettinger" <vze4rx4y at verizon.net> writes:

> In Python2.3, use itertools.islice():
>        [foo(x) for x in islice(bar, limit)]
> 
> The iterator is very fast and avoids making a copy
> of the whole sequence.  To loop to the end of the
> sequence, set limit to None.

I really must find the time to have a good look at what 2.3 has
introduced. Thanks for the pointer.