[yt-dev] advice on implementing halo member particle loading

[Ben Thompson]

Hi Britton.

Probably should not be too difficult to port across my code for that.

Sorry to also distract from the original topic too. I think the idea is
good, but I don't have much experience on the data selector side of things
myself, so I do not know how much help I would be on that part in
particular.

Ben.

On Thu, May 7, 2015 at 12:11 PM, Britton Smith <brittonsmith at gmail.com>
wrote:

> Hi Ben,
>
> I have added frontends for the outputs of a couple different halo finders
> now and found it to be pretty straightforward.  If you're interested in
> doing this, you should have a look at either the rockstar or owls_subfind
> frontends.
>
> Britton
>
> On Thu, May 7, 2015 at 11:08 AM, Ben Thompson <bthompson2090 at gmail.com>
> wrote:
>
>> +1 for this idea. I have essentially been using yt.sphere data contains
>> with the virial radius as my way of querying the particles within the halo.
>> When in fact depending on the halo finder, halos do not necessary have to
>> be spherical. Likewise rockstar and other halo finders also have machinery
>> to tell you what particles are currently in the halo too.
>>
>> On topic of halo finders, how easy do you guys think would it be to
>> implement other halo finders? Or at least be able to read in the results of
>> other halo finders? With machinery like this, it would potentially be
>> easier to "at least" include the results of other halo finders too. I have
>> been using AHF for a lot of my work recently but am currently working with
>> a custom version of the pynbody halo catalog (pretty much a direct rip but
>> using YT to handle the units upon initialisation). I imagine with machinery
>> like this it would be easier to do so.
>>
>> Ben.
>>
>> On Thu, May 7, 2015 at 11:57 AM, Britton Smith <brittonsmith at gmail.com>
>> wrote:
>>
>>> Hi everyone,
>>>
>>> Myself and one other who should be joining this list soon are interested
>>> in implementing some new functionality and I would like to solicit some
>>> advice.
>>>
>>> What we have are halo catalog datasets that, for the most part, are
>>> already loadable in yt.  They are loadable in that each individual halo is
>>> a particle such that querying the mass field returns the mass of each
>>> halo.  However, these datasets also store the particles from the simulation
>>> snapshot that are the members of each halo.  We currently do not have the
>>> machinery to query them and this is what we would like to add.
>>>
>>> It seems the most sensible idea is to create a halo data container such
>>> that something like the following returns the mass of all the particles in
>>> a halo:
>>>
>>> my_halo = ds.halo(some_id)
>>> my_halo["particle_mass"]
>>>
>>> This is somewhat different from the existing data containers as it is
>>> not geometric.  The member particles are explicitly known.  I don't have
>>> much experience with making data containers so I can't tell if this makes
>>> things easier or harder.  Anyway, this is the plan.
>>>
>>> If anyone has reasons this may be too difficult or simply not work, I
>>> would appreciate hearing them.  Any general advice or other ideas for
>>> making this functionality work would also be welcome.
>>>
>>> Thanks!
>>>
>>> Britton
>>>
>>> _______________________________________________
>>> yt-dev mailing list
>>> yt-dev at lists.spacepope.org
>>> http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
>>>
>>>
>>
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