[yt-dev] Field Parameters Bug

[Nathan Goldbaum]

On Thu, Oct 2, 2014 at 8:23 AM, Cameron Hummels <chummels at gmail.com> wrote:

> I thought that's what I originally suggested.  But wouldn't we need to do
> it in "set_field_parameter" instead? and wouldn't it be a required argument?
>

Since calls to get_field_parameter generally happen inside field
definitions and field definitions can happen *before* datasets are loaded,
this can't happen inside set_field_parameter, where that would make sense.
It would actually *almost* work, but we would need to figure out a way to
mock up appropriate units for field parameters during field detection.


>
> On Thu, Oct 2, 2014 at 8:20 AM, Matthew Turk <matthewturk at gmail.com>
> wrote:
>
>> I'd like to avoid that.
>>
>> What I was thinking was more along the lines of adding an argument to
>> get_field_parameter that optionally specified the dimensions.
>> On Oct 2, 2014 10:08 AM, "Cameron Hummels" <chummels at gmail.com> wrote:
>>
>>> So we need something akin to adding particle filters?  Define the
>>> field_parameter and then add the field_parameter?  That seems reasonable to
>>> me.
>>>
>>> On Thu, Oct 2, 2014 at 7:42 AM, Matthew Turk <matthewturk at gmail.com>
>>> wrote:
>>>
>>>> On Thu, Oct 2, 2014 at 9:41 AM, Cameron Hummels <chummels at gmail.com>
>>>> wrote:
>>>> > I like the option of just adding a "dimension" argument to when you
>>>> > declare/add a field_parameter.  That retains the freedom of making
>>>> your own
>>>> > field_parameters, but seems to fix this dimensional problem.
>>>>
>>>> We'd also need to add a step where they are added or declared that
>>>> isn't inside userspace code.
>>>>
>>>> >
>>>> > Cameron
>>>> >
>>>> > On Thu, Oct 2, 2014 at 5:36 AM, Matthew Turk <matthewturk at gmail.com>
>>>> wrote:
>>>> >>
>>>> >> Hi Hilary,
>>>> >>
>>>> >> Maybe we ought to have a registry of known field parameters,
>>>> >> affiliated with dimensions.  A while back I looked at the known ones,
>>>> >> and there were not many in use.  It might be relatively
>>>> >> straightforward to set up a simple registry.  My concern is then that
>>>> >> individuals wanting to define their own are going to run into an
>>>> issue
>>>> >> of the behavior changing, not knowing how to fix it, and so on.
>>>> >>
>>>> >> Alternately, we could use a default parameter in those failing
>>>> fields.
>>>> >> Or, we could add an argument to the add_field call of the dimensions
>>>> >> of the field parameter.
>>>> >>
>>>> >> -Matt
>>>> >>
>>>> >> On Wed, Oct 1, 2014 at 3:22 PM, Hilary Egan <hilaryye at gmail.com>
>>>> wrote:
>>>> >> > Hi all,
>>>> >> >
>>>> >> > I've encountered a bug with this example in the docs of
>>>> getting/setting
>>>> >> > field parameters of a dataset for use in a derived field. The
>>>> example
>>>> >> > works
>>>> >> > fine for known yt field parameters like bulk_velocity, but if you
>>>> change
>>>> >> > every instance of "bulk_velocity" to "my_bulk_velocity" (sample
>>>> script),
>>>> >> > then it breaks with this error.
>>>> >> >
>>>> >> > It seems as though this breaks because `has_field_parameter` always
>>>> >> > returns
>>>> >> > True, and there is no way to know ahead of time what units a
>>>> >> > user-defined
>>>> >> > field parameter will take, so the mock field data can't be set up
>>>> >> > correctly.
>>>> >> > Nathan suggested via IRC that this might necessitate creating a
>>>> way to
>>>> >> > register user-defined field parameters, but it's probably worth
>>>> >> > brain-storming about if anyone else has any other suggestions!
>>>> >> >
>>>> >> > -Hilary
>>>> >> >
>>>> >> > _______________________________________________
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>>>> >> > yt-dev at lists.spacepope.org
>>>> >> > http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
>>>> >> >
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>>>> >
>>>> >
>>>> >
>>>> >
>>>> > --
>>>> > Cameron Hummels
>>>> > Postdoctoral Researcher
>>>> > Steward Observatory
>>>> > University of Arizona
>>>> > http://chummels.org
>>>> >
>>>> > _______________________________________________
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>>>> > yt-dev at lists.spacepope.org
>>>> > http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
>>>> >
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>>>>
>>>
>>>
>>>
>>> --
>>> Cameron Hummels
>>> Postdoctoral Researcher
>>> Steward Observatory
>>> University of Arizona
>>> http://chummels.org
>>>
>>> _______________________________________________
>>> yt-dev mailing list
>>> yt-dev at lists.spacepope.org
>>> http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
>>>
>>>
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>>
>
>
> --
> Cameron Hummels
> Postdoctoral Researcher
> Steward Observatory
> University of Arizona
> http://chummels.org
>
> _______________________________________________
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> http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
>
>
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