[Numpy-discussion] Quaternion data type

Mark Wiebe mwwiebe at gmail.com
Sat May 5 16:43:13 EDT 2012

On Sat, May 5, 2012 at 1:06 PM, Charles R Harris
<charlesr.harris at gmail.com>wrote:
> On Sat, May 5, 2012 at 11:19 AM, Mark Wiebe <mwwiebe at gmail.com> wrote:
>> On Sat, May 5, 2012 at 11:55 AM, Charles R Harris <
>> charlesr.harris at gmail.com> wrote:
>>> On Sat, May 5, 2012 at 5:27 AM, Tom Aldcroft <
>>> aldcroft at head.cfa.harvard.edu> wrote:
>>>> On Fri, May 4, 2012 at 11:44 PM, Ilan Schnell <ischnell at enthought.com>
>>>> wrote:
>>>> > Hi Chuck,
>>>> >
>>>> > thanks for the prompt reply.  I as curious because because
>>>> > someone was interested in adding
>>>> http://pypi.python.org/pypi/Quaternion
>>>> > to EPD, but Martin and Mark's implementation of quaternions
>>>> > looks much better.
>>>> Hi -
>>>> I'm a co-author of the above mentioned Quaternion package.  I agree
>>>> the numpy_quaternion version would be better, but if there is no
>>>> expectation that it will move forward I can offer to improve our
>>>> Quaternion.  A few months ago I played around with making it accept
>>>> arbitrary array inputs (with similar shape of course) to essentially
>>>> vectorize the transformations.  We never got around to putting this in
>>>> a release because of a perceived lack of interest / priorities... If
>>>> this would be useful then let me know.
>>> Would you be interested in carrying Martin's package forward? I'm not
>>> opposed to having quaternions in numpy/scipy but there needs to be someone
>>> to push it and deal with problems if they come up. Martin's package
>>> disappeared in large part because Martin disappeared. I'd also like to hear
>>> from Mark about other aspects, as there was also a simple rational user
>>> type proposed that we were looking to put in as an extension 'test' type.
>>> IIRC, there were some needed fixes to Numpy, some of which were postponed
>>> in favor of larger changes. User types is one of the things we want ot get
>>> fixed up.
>> I kind of like the idea of there being a package, separate from numpy,
>> which collects these dtypes together. To start, the quaternion and the
>> rational type could go in it, and eventually I think it would be nice to
>> move datetime64 there as well. Maybe it could be called numpy-dtypes, or
>> would a more creative name be better?
> I'm trying to think about how that would be organized. We could create a
> new repository, numpy-user-types (numpy-extension-types), under the numpy
> umbrella. It would need documents and such as well as someone interested in
> maintaining it and making releases. A branch in the numpy repository
> wouldn't work since we would want to rebase it regularly. It could maybe go
> in scipy but a new package would need to be created there and it feels too
> distant from numpy for such basic types as datetime.
> Do you have thoughts about the details?

Another repository under the numpy umbrella would best fit what I'm
imagining, yes. I would imagine it as a package of additional types that
aren't the core ones, but that many people would probably want to install.
It would also be a way to continually exercise the type extension system,
to make sure it doesn't break. It couldn't be a branch of numpy, rather a
collection of additional dtypes and associated useful functions.


> Chuck
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