[yt-users] Profile of a projected quantity?

Britton Smith brittonsmith at gmail.com
Mon May 5 04:44:31 PDT 2014


Hi Matt,

Ok, that makes a lot of sense.  I think your idea would work.  If we made a
projection become a 2D dataset with only the fields that were projected
available as the base fields, this could be quite straightforward.

Britton


On Sun, May 4, 2014 at 1:34 PM, Matthew Turk <matthewturk at gmail.com> wrote:

> Hi Britton,
>
> On Sun, May 4, 2014 at 9:25 AM, Britton Smith <brittonsmith at gmail.com>
> wrote:
> > It would be cool if we were able to treat a projection as a 2D data
> > container where you could define a center, create a radius field, and
> then
> > just pipe directly into the regular profiling machinery.  How hard would
> it
> > be to do that (longer timescale than meeting Nathan's needs here of
> course)?
>
> I agree.  So I think the only reason this would be difficult is
> because of the degeneracy between asking for a derived field that
> would be derived *in the grids* and asking for a derived field that
> would be derived *in the data object*.  Typically, we always assume
> that the data object can generate derived fields -- effectively, what
> this means is that if you ask for velocity magnitude, the velocity
> magnitude can be derived from the x-y-z velocities in the data object
> and that it doesn't need to go back to the individual
> chunks/grids/particles.  This is how slices work, but projections
> don't because we assume the act of projecting is how the data is
> generated.  ("Construction" versus "selection" data objects.)
>
> So if we can break that degeneracy -- having a way to say, this object
> *has* everything we need to do the derived fields, so do them in it,
> then I think we can implement it.  I think it's mostly a nomenclature
> thing.  What if we were able to make projections serve as a source to
> another data object?  Would that suffice?
>
> >
> >
> > On Thu, May 1, 2014 at 2:34 PM, Nathan Goldbaum <nathan12343 at gmail.com>
> > wrote:
> >>
> >>
> >>
> >> On Thu, May 1, 2014 at 8:07 AM, Cameron Hummels <chummels at gmail.com>
> >> wrote:
> >>>
> >>> I have some scripts for doing projected radius profiles using
> projections
> >>> and FRBs.  They'll certainly be different from the Profile1D stuff,
> but they
> >>> work OK.  I'm happy to share them if you want a starter for this
> avenue.
> >>
> >>
> >> Would love to see them.
> >>
> >>>
> >>>
> >>> Cameron
> >>>
> >>>
> >>> On Wed, Apr 30, 2014 at 6:24 PM, Matthew Turk <matthewturk at gmail.com>
> >>> wrote:
> >>>>
> >>>> Hi Nathan,
> >>>>
> >>>> On Wed, Apr 30, 2014 at 8:35 PM, Nathan Goldbaum <
> nathan12343 at gmail.com>
> >>>> wrote:
> >>>> > Hi all,
> >>>> >
> >>>> > Is there a way for me to find a profile using a projection as a data
> >>>> > source?
> >>>> > In particular, I'd like to find a radial profile of a surface
> density
> >>>> > in a
> >>>> > disk galaxy simulation.
> >>>> >
> >>>> > I think I could do this by histogramming a fixed resolution buffer
> >>>> > created
> >>>> > by a projection data source but is that the only way to do it?  I'd
> >>>> > prefer
> >>>> > for my data pipeline to look identical for computing profiles and in
> >>>> > all
> >>>> > other cases I'm using a Profile1D object to find things like the
> >>>> > cumulative
> >>>> > mass or the average density as a function of radius.
> >>>>
> >>>> I believe this is what has been done in the past -- Sam wrote a set of
> >>>> scripts that did it this way.  I think, though, that you might be able
> >>>> to use the cylindrical radius derived fields and then accumulate
> >>>> within them.  Would that get to where you want the analysis?
> >>>>
> >>>> -Matt
> >>>>
> >>>> >
> >>>> > Thanks for your help with this!
> >>>> >
> >>>> > -Nathan
> >>>> >
> >>>> > _______________________________________________
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> >>>> >
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> >>>
> >>>
> >>>
> >>>
> >>> --
> >>> Cameron Hummels
> >>> Postdoctoral Researcher
> >>> Steward Observatory
> >>> University of Arizona
> >>> http://chummels.org
> >>>
> >>> _______________________________________________
> >>> yt-users mailing list
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> >>>
> >>
> >>
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