[Numpy-discussion] Why are empty arrays False?

Chris Barker chris.barker at noaa.gov
Tue Aug 22 17:48:14 EDT 2017


On Tue, Aug 22, 2017 at 11:04 AM, Michael Lamparski <
diagonaldevice at gmail.com> wrote:

> I think truthiness is easily a wart in any dynamically-typed language (and
> yet ironically, every language I can think of that has truthiness is
> dynamically typed except for C++).  And yet for some reason it seems to be
> pressed forward as idiomatic in python, and for that reason alone, I use
> it.
>

me too :-)


> Meanwhile, for an arbitrary iterator taken as an argument, if you want it
> to have at least one element for some reason, then good luck; truthiness
> will not help you.
>

of course, nor will len()

And this is mostly OK, as if you are taking an aritrary iterable, then you
are probably going to, well, iterate over it, and:

for this in an_empty_iterable:
    ...

works fine.

But bringing it  back OT -- it's all a bit messy, but there is logic for
the existing conventions in numpy -- and I think backward compatibility is
more important than a slightly cleaner API.

-CHB



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Christopher Barker, Ph.D.
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