[Numpy-discussion] numpy scalars and savez -- bug?

Chris Barker - NOAA Federal chris.barker@noaa....
Fri Apr 19 10:03:18 CDT 2013


On Apr 18, 2013, at 11:33 PM, Nathaniel Smith <njs@pobox.com> wrote:

On 18 Apr 2013 01:29, "Chris Barker - NOAA Federal" <chris.barker@noaa.gov>
wrote:
> This has been annoying, particular as rank-zero scalars are kind of a
pain.

BTW, while we're on the topic, can you elaborate on this? I tend to think
scalars (as opposed to 0d ndarrays) are kind of a pain, so I'm curious if
you have specific issues you've run into with 0d ndarrays.

Well, I suppose what's really a pain is that we have both, and they are not
the same, and neither can be used in all cases one may want.

In the case at hand, I really wanted a datetime64 scalar. By saving and
re-loading in an npz, it got converted to a rank-zero array, which had
different behavior. In this case, the frustrating bit was how to extract a
scalar again ( which I really wanted to turn into a datetime object).

After the fact, I discovered .item(), which seems to do what I want.

On a phone now, so sorry about the lack of examples.

Note: I've lost track of why we need both scalers and rank-zero arrays. I
can't help thinking that there could be an object that acts like a scalar
in most contexts, but also has the array methods that make sense.

But I know it's far from simple.

-Chris
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