[yt-users] Recenter Halo

[Chen Jingjing]

Hi Britton,
I tried to use the iterative_center_of_mass callback like this. Since you
said it does not require a sphere callback, I assumed that I don't need to
specify a sphere.

data_ds = yt.load('RD0008/RedshiftOutput0008')

hc = HaloCatalog(data_ds=data_ds, finder_method='hop')

hc.add_callback("iterative_center_of_mass")

hc.add_filter("quantity_value", "particle_mass", ">", 1e11, "Msun")

hc.create()

I got a error

NameError: global name 'periodic_distance' is not defined

So can you tell me what would be the right way?

Thanks,
Jingjing

2015-03-30 15:08 GMT-04:00 Britton Smith <brittonsmith at gmail.com>:

> Hi Jingjing,
>
> To add that function to the HaloCatalog analysis, you need to do the
> following:
>
> hc.add_callback("sphere_field_max_recenter", "density")
>
> Note, this callback recenters an existing sphere, so you will need to have
> added a sphere with:
>
> hc.add_callback("sphere")
>
> Make sure you add the sphere first.  Additionally, you might try the
> "iterative_center_of_mass" callback, which will calculate new centers by
> calculating the center of mass on a continually smaller sphere.  This one
> does not require a sphere callback and will actually write out the
> recentered positions.
>
> Britton
>
> On Mon, Mar 30, 2015 at 7:27 PM, Chen Jingjing <chenjj235 at gmail.com>
> wrote:
>
>> Dear yt-users,
>> I am having a little problem on finding the exact center of a halo. I
>> used to do
>>
>> "hc = HaloCatalog(data_ds=data_ds, finder_method='hop')"
>>
>> to create a halo catalog. But I think the position in the catalog is a
>> little bit off the exact center judging from the plots I made. I need the
>> exact center to compute the angular momentum so the off-center result could
>> cause some problem. I tried to recenter at the maximum gas density by
>> adding this line
>>
>> "hc.sphere_field_max_recenter('density')"
>>
>> But I got an error, AttributeError: 'HaloCatalog' object has no attribute
>> 'sphere_field_max_recenter'.
>>
>> Can anyone tell me what is the right way to find the center as the
>> location of maximum gas density?
>>
>> Thanks,
>> Jingjing
>>
>>
>>
>> --
>>
>> Jingjing Chen [ chenjj235 at gmail.com ]
>> Department of Astronomy
>> Columbia University
>> 550 West 120th Street
>> New York, New York 10027
>> Cell Phone: +1(347)5746709
>>
>>
>> _______________________________________________
>> yt-users mailing list
>> yt-users at lists.spacepope.org
>> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>>
>>
>
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>


-- 

Jingjing Chen [ chenjj235 at gmail.com ]
Department of Astronomy
Columbia University
550 West 120th Street
New York, New York 10027
Cell Phone: +1(347)5746709
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