[Numpy-discussion] Notes from the numpy dev meeting at scipy 2015

[Nathaniel Smith]

On Tue, Aug 25, 2015 at 12:21 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> On Tue, 25 Aug 2015 03:03:41 -0700
> Nathaniel Smith <njs at pobox.com> wrote:
>>
>> Supporting third-party dtypes
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
> [...]
>>
>>   Some features that would become straightforward to implement
>>   (e.g. even in third-party libraries) if this were fixed:
>>   - missing value support
>>   - physical unit tracking (meters / seconds -> array of velocity;
>>     meters + seconds -> error)
>>   - better and more diverse datetime representations (e.g. datetimes
>>     with attached timezones, or using funky geophysical or
>>     astronomical calendars)
>>   - categorical data
>>   - variable length strings
>>   - strings-with-encodings (e.g. latin1)
>>   - forward mode automatic differentiation (write a function that
>>     computes f(x) where x is an array of float64; pass that function
>>     an array with a special dtype and get out both f(x) and f'(x))
>>   - probably others I'm forgetting right now
>
> It should also be the opportunity to streamline datetime64 and
> timedelta64 dtypes. Currently the unit information is IIRC hidden in
> some weird metadata thing called the PyArray_DatetimeMetaData.

Yeah, and PyArray_DatetimeMetaData is an "NpyAuxData", which is its
own personal little object system implemented in C with its own
reference counting system... the design of dtypes has great bones, but
the current implementation has a lot of, um, historical baggage.

-n

-- 
Nathaniel J. Smith -- http://vorpus.org