[yt-users] halo finding on subvolumes

[Stephen Skory]

Hi all,

I have just pushed a change to the mercurial repo that should allow halo finding on subvolumes with all three of the finders in yt. Some of you have asked for this, so I hope it's helpful! This is fairly alpha work, so if you want to use it, please use it with caution. Double-check the results to make sure things make sense. I will not be surprised if something doesn't work, so please do let me know if you run into a problem. As far as I can tell, it works in serial and in parallel on subvolumes, which may be handy.

Here's a quick example of how to use it. Basically, the subvolume you define needs to be "comfortably" larger than the region over which you which to find halos. "Comfortable" means perhaps 10% larger on each side, but you can experiment with that. If you don't define a 'subvolume', it will default to the full box, which is how the halo finders have behaved all along. Oh, and the region has to be a "region" not a "sphere" or anything non-rectilinear like that.

----

from yt.mods import *
from yt.analysis_modules.halo_finding.api import *

pf = load('data0458')

sv = pf.h.region([0.5]*3, [0.21, .21, .72], [.28, .28, .79])
halos = HaloFinder(pf, subvolume = sv)
halos.write_out("sv.out")

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You use the same "subvolume" construction with the other halo finders.
 

Stephen Skory
s at skory.us
http://stephenskory.com/
510.621.3687 (google voice)