[yt-users] ProjectionPlot of a new field

Geoffrey So gsiisg at gmail.com
Tue Feb 25 12:34:47 PST 2014 

"It probably doesn't waste that much."

"add_field("Grey_Radiation_source", function=grey_radiation_function,
convert_function=grey_radiation_convert_function, take_log=True,
unts="erg\/s**{-1}")"

Even with Nathan's suggestion I'll still need to define a
grey_radiation_function, and that's what I was trying to avoid. However,
Matt says it won't be that much more expensive, so I'll just go with my
original defining a new field by multiplying the original field by
constants.

Sorry for the trouble.

From
G.S.


On Tue, Feb 25, 2014 at 12:01 PM, Nathan Goldbaum <nathan12343 at gmail.com>wrote:

> The units for the field are generated from the unit string.  This
> needs to be defined in the call to add_field for
> "Grey_Radiation_Source".  The unit string should be in LaTeX format.
> Something like:
>
> add_field("Grey_Radiation_source", function=grey_radiation_function,
> convert_function=grey_radiation_convert_function, take_log=True,
> unts="erg\/s**{-1}")
>
> where grey_radiation_function and grey_radiation_convert_function are
> python functions with the correct signature and return values expected
> for field definitions and field conversion functions.
>
> As sam suggested, you might want to define a convert_function for this
> field to handle the constant conversions you want to apply.
>
> See here:
> http://yt-project.org/docs/dev/analyzing/creating_derived_fields.html
>
> In unitrefactor this is all more streamlined so that units can be
> dynamically modified and unit strings for plots are generated based on
> the data not a hard-coded LaTeX string.
>
> Cheers,
>
> Nathan
>
> On Tue, Feb 25, 2014 at 11:51 AM, Geoffrey So <gsiisg at gmail.com> wrote:
> > Not trying to do anything too fancy, just trying to put units on the
> > colorbar since the field does not have build in cgs conversion factors in
> > Enzo.  I multiply the plot by the conversion factors but the text on the
> > colorbar says 'unknown' for units.  I can bypass this by defining a
> derived
> > field by using the original field and multiplied by the same constants,
> and
> > including the correct units there, but that seems to waste a lot of
> > computation.
> >
> > From
> > G.S.
> >
> > convD = pf.conversion_factors["Density"]
> > convV = pf.conversion_factors["x-velocity"]
> > z     = pf["CosmologyCurrentRedshift"]
> >
> > field = 'Grey_Radiation_Energy'
> >
> > prj = ProjectionPlot(pf, direct, field, center='c',
> >                      weight_field=field,
> >                      fontsize=24)
> >
> > # multiply by conversion factors to get erg cm^{-3}
> > prj.data_source['Grey_Radiation_Energy'] *= convD*convV*convV
> >
> > prj.annotate_text((1.05,1.05),'z=%2.2f' % z)
> >
> > prj.set_log(field,'log')
> >
> > prj.save('frames/')
> >
> >
> > On Mon, Feb 24, 2014 at 6:56 PM, Nathan Goldbaum <nathan12343 at gmail.com>
> > wrote:
> >>
> >> Hi Geoffrey,
> >>
> >> It depends on what you're trying to do.
> >>
> >> Can you share the script you're working on?
> >>
> >> -Nathan
> >>
> >> On Mon, Feb 24, 2014 at 6:24 PM, Geoffrey So <gsiisg at gmail.com> wrote:
> >> > A follow-up question,
> >> >
> >> > Is there a way to change the labels on the x, y axes and colorbar
> text?
> >> >
> >> > From
> >> > G.S.
> >> >
> >> >
> >> > On Mon, Feb 24, 2014 at 5:31 PM, Geoffrey So <gsiisg at gmail.com>
> wrote:
> >> >>
> >> >> Hi Sam,
> >> >>
> >> >> I might be mistaken but it seems the convert_function requires there
> to
> >> >> be
> >> >> already a cgs conversion factor YT knows about, and unfortunately
> this
> >> >> field
> >> >> I'm working with does not have that.  What I used to do is just
> >> >> multiply the
> >> >> conversion factors in after making the FRB, but I'm starting to try
> to
> >> >> using
> >> >> the new Projection/PhasePlot.
> >> >>
> >> >> I tried the script you have up there, and I think it is doing the
> same
> >> >> thing I was with the FRB.  At least I see the colorbar also changed
> >> >> accordingly, which is exactly what I hoped for, thanks!
> >> >>
> >> >> From
> >> >> G.S.
> >> >>
> >> >>
> >> >>
> >> >> On Mon, Feb 24, 2014 at 4:52 PM, Sam Skillman <samskillman at gmail.com
> >
> >> >> wrote:
> >> >>>
> >> >>> Hi Geoffrey,
> >> >>>
> >> >>> Yes, it would save time to multiply the projection object by a
> >> >>> constant
> >> >>> factor if your projection has already been done. However, it is a
> bit
> >> >>> dangerous to do this since now you need to manually edit how all the
> >> >>> units/labels work out.
> >> >>>
> >> >>> I'd suggest just creating a new derived field that uses the
> >> >>> convert_function option
> >> >>>
> >> >>> (
> http://yt-project.org/docs/dev/analyzing/creating_derived_fields.html#field-options
> ).
> >> >>> A good, non-trivial example is the SZY field:
> >> >>>
> >> >>>
> >> >>>
> https://bitbucket.org/yt_analysis/yt/src/61e6b84f875cc8fcf25b5b1e67ddd501a19daf68/yt/data_objects/universal_fields.py?at=yt#cl-577
> >> >>>
> >> >>> If you do want to manually modify an projection object, you can do
> >> >>> something like the following:
> >> >>>
> >> >>> from yt.mods import *
> >> >>> pf = load('IsolatedGalaxy/galaxy0030/galaxy0030')
> >> >>> proj_pw = ProjectionPlot(pf, 0, 'Density', weight_field='Density')
> >> >>> proj_pw.save('before')
> >> >>> proj_pw.data_source['Density'] *= 1.5
> >> >>> proj_pw.refresh()
> >> >>> proj_pw.save('after')
> >> >>>
> >> >>> Sam
> >> >>>
> >> >>>
> >> >>>
> >> >>> On Mon, Feb 24, 2014 at 12:26 PM, Geoffrey So <gsiisg at gmail.com>
> >> >>> wrote:
> >> >>>>
> >> >>>> Hi all,
> >> >>>>
> >> >>>> Will I be saving computation time by multiplying some constant
> >> >>>> conversion factors on the projection object instead of creating a
> >> >>>> derived
> >> >>>> field with an existing field multiplied by the factors?
> >> >>>>
> >> >>>> And how would I go about multiplying the projection by some
> factors?
> >> >>>>
> >> >>>> If there's no significant saving I'll just do the derived field.
> >> >>>>
> >> >>>> From
> >> >>>> G.S.
> >> >>>>
> >> >>>> _______________________________________________
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> >> >>>>
> >> >>>
> >> >>>
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