[Numpy-discussion] Quaternion data type

Charles R Harris charlesr.harris at gmail.com
Sat May 5 14:06:12 EDT 2012

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?

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