On Mon, Apr 20, 2020 at 08:42:00PM +0300, Ram Rachum wrote:
> Here's something that would have saved me some debugging yesterday:
>
> >>> zipped = zip(x, y, z, strict=True)
>
> I suggest that `strict=True` would ensure that all the iterables have been
> exhausted, raising an exception otherwise.
Here you go, add this to your personal toolbox:
from itertools import zip_longest
def zip_strict(*iterables):
sentinel = object()
for t in zip_longest(*iterables, fillvalue=sentinel):
if sentinel in t:
p = t.index(sentinel)
msg = "argument %d exhausted"
raise ValueError(msg % p)
yield t
I added that to my personal toolbox sometime, oh, eight years or so ago,
and have never used it since, so it's brand new :-)
> This is useful in cases where you're assuming that the iterables all have
> the same lengths. When your assumption is wrong, you currently just get a
> shorter result, and it could take you a while to figure out why it's
> happening.
That assumes that you care that the assumption is wrong, rather than
just saying "... if they aren't the same length, truncate at the
shortest iterable".
Can you give a little more detail on your use-case where the consumer of
the data needs to care that all the iterables are the same length?
This approach has (at least) one **big** problems as far as I am
concerned:
- it rules out the use of infinite iterators like itertools.count()
> What do you think?
I'm tempted to say YAGNI, which would be a pretty brave thing to say
given that you just said you did need it :-)
--
Steven
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