[yt-users] Obtaining projection data value

[Jun-Hwan Choi]

Hi Matthew,

I try the following script
from yt.mods import *
import matplotlib.pylab as pylab

# load up a dataset
index = 30
pf = load("DD%04d/DD%04d" % (index,index))
all_center = pf.h.find_max("Density")[1]
#sphere = pf.h.sphere(all_center, (50, 'pc'))
#sphere_center = sphere.quantities["CenterOfMass"]()

# create density slices   
proj = pf.h.proj(2, 'Density')
width = 100/pf['pc']
res = [1000,1000]
frb = proj.to_frb(width, res, center=all_center)

pylab.imshow(frb['Density'])
pylab.xlabel(r'$x\ \mathrm{pc}$')
pylab.ylabel(r'$x\ \mathrm{furlongs}$')
pylab.savefig('my_perfect_figure.png')

and I got following error message:
frb = proj.to_frb(width, res, center=sphere_center)
AttributeError: 'AMRQuadTreeProj' object has no attribute 'to_frb'

What does error mean?

Thank you,
Junhwan
Matthew Turk wrote:
> Hi Jun-Hwan,
>
> On Mon, Feb 6, 2012 at 4:09 PM, Jun-Hwan Choi <jhchoi at pa.uky.edu> wrote:
>   
>> Hi all,
>>
>> I wonder whether that I can obtain the value that generate projection plot.
>> I can make a projection image for my disk using add_projection  in the
>> plot_collation.
>> I am interested in to get the projected density value and its position (and
>> its pixel size) to perform the FFT analysis in order to find the
>> non-axisymmertic feature such as disk-bar.
>> Is there way to get this values using yt?
>>     
>
> Yes.
>
> http://yt-project.org/docs/2.3/visualizing/manual_plotting.html
> http://yt-project.org/docs/2.3/analyzing/generating_processed_data.html#d-image-arrays
>
> The function you're looking for is "to_frb" which is a method on the
> projection object.
>
> pf = load(...)
> proj = pf.h.proj(axis, field, weight)
> frb = proj.to_frb()
> field = frb[field]
>
> -Matt
>
>   
>> Thank you in advance,
>> Junhwan
>>
>> --
>> --------------------------------------------------------------
>> Jun-Hwan Choi, Ph.D.
>> Department of Physics and Astronomy, University of Kentucky
>> Tel: (859) 897-6737        Fax: (859) 323-2846
>> Email: jhchoi at pa.uky.edu   URL: http://www.pa.uky.edu/~jhchoi
>> --------------------------------------------------------------
>>
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-- 
--------------------------------------------------------------
Jun-Hwan Choi, Ph.D.
Department of Physics and Astronomy, University of Kentucky
Tel: (859) 897-6737        Fax: (859) 323-2846
Email: jhchoi at pa.uky.edu   URL: http://www.pa.uky.edu/~jhchoi
--------------------------------------------------------------