[yt-users] yt.lagrangian_volume

[Cameron Hummels]

Oops.  I just saw that you did include the outputs.  Let me look into this
and get back to you in a moment.

Cameron

On Tue, Oct 28, 2014 at 12:56 PM, Cameron Hummels <chummels at gmail.com>
wrote:

> Hi Jingjing,
>
> I'm sorry that you're running into some problems with
> yt.lagrangian_region. Let me see if I can help you.
>
> The output of the code should return a box in code units containing all of
> the DM particles in the selected halo.  I've only tested this with enzo
> outputs (and I believe that is what you're using it on too), so those code
> units will go from 0 to 1 in x, y, z.  In addition to this output, the code
> also will recenter these coordinates so that the final halo coordinates
> will sit at 0.5, 0.5, 0.5 at the center of the box.  It provides the
> original box shifted over in coordinates to accomodate this recentering.
> Lastly, you are correct that some of the coordinates will go above 1 in
> cases when the particles shift over the periodic boundary condition.
>
> Do your results make more sense given this information?  If you're still
> confused, can you send us the text of your outputs, so that we can try to
> figure them out?
>
> I'm actually working on a newer version of this which will work with yt
> 3.0 as part of a larger effort to make efficient zoom simulations, but I've
> not yet finished working on it.  I'll make sure to announce it here when
> this is complete and ready.
>
> Cameron
>
>
> On Tue, Oct 28, 2014 at 12:00 PM, Chen Jingjing <chenjj235 at gmail.com>
> wrote:
>
>> Hi,
>> I am using the code yt.lagrangian_volume to trace the box that contains
>> the dark matter particles at an early stage(higher redshift). But I was
>> quite confused about the output. I am attaching the output file below.
>> (1) I don't know what the values for the box in the new frame mean, i.e.
>> what is the unit of these values? It seems to be the normalized scale
>> because the values are about 1. But it does not seem to be normalized too
>> because there are some values that are larger than 1. Is that due to the
>> periodicity of the box?
>> (2) The bounding box and box in the new frame seems to have the same
>> size. The difference between the two box is just translation. But I was
>> expecting that the box should be expanding/collapsing.
>> (3) The COM (center of mass) in the output is within neither of the box.
>>
>> Does anyone know how to explain the box values in the output file?
>>
>> 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
>>
>>
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>>
>>
>
>
> --
> Cameron Hummels
> Postdoctoral Researcher
> Steward Observatory
> University of Arizona
> http://chummels.org
>



-- 
Cameron Hummels
Postdoctoral Researcher
Steward Observatory
University of Arizona
http://chummels.org
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