Good use for itertools.dropwhile and itertools.takewhile
rosuav at gmail.com
Wed Dec 5 14:45:05 CET 2012
On Wed, Dec 5, 2012 at 12:17 PM, Nick Mellor <thebalancepro at gmail.com> wrote:
> takewhile mines for gold at the start of a sequence, dropwhile drops the dross at the start of a sequence.
When you're using both over the same sequence and with the same
condition, it seems odd that you need to iterate over it twice.
Perhaps a partitioning iterator would be cleaner - something like
def partitionwhile(predicate, iterable):
iterable = iter(iterable)
val = next(iterable)
if not predicate(val): break
raise StopIteration # Signal the end of Phase 1
for val in iterable: yield val # or just "yield from iterable", I think
Only the cold hard boot of reality just stomped out the spark of an
idea. Once StopIteration has been raised, that's it, there's no
"resuming" the iterator. Is there a way around that? Is there a clean
way to say "Done for now, but next time you ask, there'll be more"?
I tested it on Python 3.2 (yeah, time I upgraded, I know).
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