python-quantities-developers team mailing list archive

[Darren Dale <dsdale24@xxxxxxxxx>]

On Mon, Feb 9, 2009 at 9:22 PM, John Salvatier <jsalvatier@xxxxxxxxx> wrote:

> Sounds good.
>
> Here are some miscellaneous notes:
>
>    1. In the tutorial, the part describing simplification in unambiguous
>    situations is vague. It might be good to say that "unambiguous" means the
>    units cancel directly
>    2. I still think units when printed need more spacing between terms.
>    The units term seems cramped
>
>
What do think would look better?

>
>    1. Is there a general rule for how plural vs. non-plural unit names are
>    handled by quantities? I ask because f = Quantity(1, 'feet') works but the
>    UnitQuantity feet is not defined (so q = 1* feet does not work). It might be
>    useful to mention how this works in the tutorial as this seems like the sort
>    of thing that could frustrate new users. Alternatively, Quantities could
>    define a bunch of common plural units, but this seems like a lot of extra
>    variables.
>
> Yeah, it is maybe a bit confusing. I'll add a note in the documentation
that plural variants for unit names are only available through strings for
now. If there is a big demand for plural variants, they can be added later.


> Can you tell me which numpy mailing list you will be posting to? I would
> like to sign up so I can listen to the discussion.
>

There is only the one list- numpy-discussion


> Have you thought about what you want to do with ufuncs?
>

ugh. We can't use __array_wrap__ because ufuncs do not provide an analogous
hook for preprocessing input, only post-processing. Also, numpy segfaults
when it is passed an ndarray subclass with out=None. I reported it to the
numpy maililng list but didn't get a response.

I think we need a more elegant way to handle ufuncs, using wrappers like is
done in ma. There is a lot of repetitive stuff that needs to be done. For
example, we need to make sure that if out is used, we are not attempting an
operation that modifies the units in place unless out owns its own data.
Also, passing magnitudes to the ufunc, or short-circuiting to the
numpy.ufunc if quantities are not passed could be handled by wrapper code.

I dont think its too important to address these remaining ufunc issues
before requesting comments. Although, I think we need to implement
concatenate and sqrt.

One further thought: is there an easy way to generate a list of all the
> units and constants with descriptions in the documentation? If so, I think
> it would be useful to have on the doc page.
>

That would be useful. I'm not sure, I'll have to look into it.

I noticed today that running setup.py install was doing an egg install on my
computer at work, and that eric4 was not able to run scripts because of some
issue with the egg. The scripts ran fine from the shell. I'm so sick of all
the subtle problems associated with setuptools, and with setuptools lack of
maintainance. Before making an announcement I'm going to remove support for
setuptools and add support to run the tests the same way numpy and scipy
does it.

Darren


> Best Regards,
> John
>
> On Mon, Feb 9, 2009 at 12:41 PM, Darren Dale <dsdale24@xxxxxxxxx> wrote:
>
>> I added support for customizable default units today. Yesterday I did a
>> bit of work to use numpy's sphinx extensions so we can pass through numpy's
>> docstrings and document the API with sphinx, I changed the documentation
>> decorator a little bit, extended the tutorial, implemented the regular
>> expression to properly convert integer powers to unicode superscript
>> characters, squashed a bunch of bugs, and there are some other improvements
>> I'm forgetting at the moment. I posted some new snapshots at
>> packages.python.org/quantities, please give them a try and let me know if
>> you find any problems.
>>
>> I would like to post a request for comment at numpy discussion in the next
>> couple of days. I dont think I'm going to make any more changes to the
>> codebase for now, and I'm not planning to tag any new releases, but I need
>> to put a page together discussing how the package is designed. When thats
>> done, and the snapshots have seen some use, I'll make an announcement on the
>> numpy mailing list, hopefully next monday.
>>
>> Darren
>>
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