Hi, Regarding hop + yt... 1. Does anyone know where to change the default overdensity of 160.0 ? 2. Is it (160.0) the Delta-peak, as defined in the 1998 HOP paper ? 3. I have done 512^3 grid, 512^3 dark-matter (dm) particle Enzo Cosmology Simulations in a 200 Mpc/h Box using wmap5 parameters... http://lambda.gsfc.nasa.gov/product/map/dr3/params/lcdm_sz_lens_wmap5.cfm I want to merge particles to represent atleast galaxies (Bigger groups are welcome too). What should I choose in place of 160.0 ? Will Delta-peak and Delta-outer adjust accordingly ? regards shankar KU Cosmology
I mean... Will Delta-SADDLE and Delta-outer adjust accordingly ? shankar -----Original Message----- From: yt-users-bounces@lists.spacepope.org on behalf of Agarwal, Shankar Sent: Sun 6/28/2009 3:35 PM To: yt-users@lists.spacepope.org Subject: [yt-users] HOP overdensity parameter Hi, Regarding hop + yt... 1. Does anyone know where to change the default overdensity of 160.0 ? 2. Is it (160.0) the Delta-peak, as defined in the 1998 HOP paper ? 3. I have done 512^3 grid, 512^3 dark-matter (dm) particle Enzo Cosmology Simulations in a 200 Mpc/h Box using wmap5 parameters... http://lambda.gsfc.nasa.gov/product/map/dr3/params/lcdm_sz_lens_wmap5.cfm I want to merge particles to represent atleast galaxies (Bigger groups are welcome too). What should I choose in place of 160.0 ? Will Delta-peak and Delta-outer adjust accordingly ? regards shankar KU Cosmology _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
Shankar,
1. Does anyone know where to change the default overdensity of 160.0 ?
Run it like this for a threshold of 100:
haloes = HaloFinder(pf,threshold=100.0)
By the way, you can see the available inputs and defaults to any function in Python by using help(), so
help(HaloFinder)
would get you something like this (there is more output than this, but I'm not quoting it for brevity). class HOPHaloFinder(GenericHaloFinder, HOPHaloList) | Method resolution order: | HOPHaloFinder | GenericHaloFinder | yt.lagos.ParallelTools.ParallelAnalysisInterface | HOPHaloList | HaloList | __builtin__.object | | Methods defined here: | | __init__(self, pf, threshold=160, dm_only=True, padding=0.02)
2. Is it (160.0) the Delta-peak, as defined in the 1998 HOP paper ?
No. Threshold corresponds to delta outer. Following the recommendations of the paper, delta merge = 2.5 * threshold, and delta peak = 3 * threshold. If you wish to change this, you'll have to edit lines 114 and 115 in hop_regroup.c and re-build yt by running 'python setup.py install' when in the yt-trunk-svn directory.
3. I have done 512^3 grid, 512^3 dark-matter (dm) particle Enzo Cosmology Simulations in a 200 Mpc/h Box using wmap5 What should I choose in place of 160.0 ?
There is no 'correct' answer to this question. You need to see if the haloes provided are what you want. For example, if you want low-mass haloes, you should see if there are enough found by HOP. If not, you could try lowering the threshold. Halo finders are never definitive, you must interpret the results and decide if they give you what you need. Good luck! _______________________________________________________ sskory@physics.ucsd.edu o__ Stephen Skory http://physics.ucsd.edu/~sskory/ _.>/ _Graduate Student ________________________________(_)_\(_)_______________
Thanks Stephen, that helped. By the way, do you know the thickness of the slices one gets using... pc.add_slice("Density",0) I tried help(add_slice) but obviously it doesnot work. Trouble shooting is a little tricky. Also, is this the correct place to get S2plot... http://astronomy.swin.edu.au/s2plot/index.php?title=S2PLOT:Python Any chances of making it part of yt repository? shankar -----Original Message----- From: yt-users-bounces@lists.spacepope.org on behalf of Stephen Skory Sent: Sun 6/28/2009 9:53 PM To: Discussion of the yt analysis package Subject: Re: [yt-users] HOP overdensity parameter Shankar,
1. Does anyone know where to change the default overdensity of 160.0 ?
Run it like this for a threshold of 100:
haloes = HaloFinder(pf,threshold=100.0)
By the way, you can see the available inputs and defaults to any function in Python by using help(), so
help(HaloFinder)
would get you something like this (there is more output than this, but I'm not quoting it for brevity). class HOPHaloFinder(GenericHaloFinder, HOPHaloList) | Method resolution order: | HOPHaloFinder | GenericHaloFinder | yt.lagos.ParallelTools.ParallelAnalysisInterface | HOPHaloList | HaloList | __builtin__.object | | Methods defined here: | | __init__(self, pf, threshold=160, dm_only=True, padding=0.02)
2. Is it (160.0) the Delta-peak, as defined in the 1998 HOP paper ?
No. Threshold corresponds to delta outer. Following the recommendations of the paper, delta merge = 2.5 * threshold, and delta peak = 3 * threshold. If you wish to change this, you'll have to edit lines 114 and 115 in hop_regroup.c and re-build yt by running 'python setup.py install' when in the yt-trunk-svn directory.
3. I have done 512^3 grid, 512^3 dark-matter (dm) particle Enzo Cosmology Simulations in a 200 Mpc/h Box using wmap5 What should I choose in place of 160.0 ?
There is no 'correct' answer to this question. You need to see if the haloes provided are what you want. For example, if you want low-mass haloes, you should see if there are enough found by HOP. If not, you could try lowering the threshold. Halo finders are never definitive, you must interpret the results and decide if they give you what you need. Good luck! _______________________________________________________ sskory@physics.ucsd.edu o__ Stephen Skory http://physics.ucsd.edu/~sskory/ _.>/ _Graduate Student ________________________________(_)_\(_)_______________ _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
Hi Shankar,
pc.add_slice("Density",0)
Slices are infinitesimally small - the cells are only those cells that intersect with the slices are returned. If you want more than that, you'd want a projection through a thin slab, similar to what Britton Smith uses in the lightcone generator in yt/extensions.
I tried help(add_slice) but obviously it doesnot work. Trouble shooting is a little tricky.
help(pc.add_slice) is what you would be looking for, but that unfortunately does not explicitly say that the slices are infinitesimally thin.
Also, is this the correct place to get S2plot... http://astronomy.swin.edu.au/s2plot/index.php?title=S2PLOT:Python
Yup
Any chances of making it part of yt repository?
If you mean making it a part of the yt source repository, I would say no, there is no chance. Making it a part of the installation script is also not terribly likely, because there are some things in the S2Plot installation that I'm not really comfortable automating. (And beyond that, we would have to wait for a relatively permissive open source license before including it as a dependency.) That being said, future versions of the installation script may include VTK, but I'm not ready to commit to that at this time. Additional methods of volume rendering and 3D plotting are also being explored. -Matt
participants (3)
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Agarwal, Shankar
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Matthew Turk
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Stephen Skory