Hi, I am generating Halos using HOP (via yt). I see that the default overdensity is 160. I guess it means 160 particles per cell.

But isn't cell size a function of the simulation box volume and the grid ? For example, if Box=200Mpc and Ngrid=512^3, then cell=(0.390625 Mpc)^3 Isn't 0.390625 Mpc too big for a galaxy ?

What is the calculation behind 160 ?

Hello everyone:   I upgraded to the new version of yt, and I noticed there was a change in unit designation.  I used to be able to specify units in comoving units of kpc as: "kpccm", but that functionality now appears to be broken.  Does anyone know what the new syntax is for using comoving units? Here is a code example that used to work, but it no longer does in the new version: pf = EnzoStaticOutput(filename) thick_faceon =  10.0/pf['kpccm']                                                                     Thanks!                                                                     Cameron -- Cameron Hummels PhD Candidate, Astronomy Department of Columbia University Public Outreach Director, Astronomy Department of Columbia University NASA IYA New York State Student Ambassador http://outreach.astro.columbia.edu _______________________________________________ yt-users mailing list yt-users(a)lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org

Hi Matt:     Here are my outputs in 1.5 and trunk iyt: ----------------------------------------------------------- In [1]: pf = load("L20S2D9H26S_0050") In [2]: pf["kpccm"] --------------------------------------------------------------------------- KeyError                                  Traceback (most recent call last) /u/ac/chummels/source/yt-x86_64/src/yt-1.5/scripts/iyt in <module>() ----> 1       2       3       4       5 /u/ac/chummels/source/yt-x86_64/src/yt-1.5/yt/lagos/OutputTypes.pyc in __getitem__(self, key)     104                   self.conversion_factors]:     105             if key in d: return d[key] --> 106         raise KeyError(key)     107     108     def keys(self): KeyError: 'kpccm' In [3]: pf["ComovingCoordinates"] Out[3]: 1 ---------------------------------------------------------------------- My enzo parameter file also has the comoving coordinates flag set as yours does.  Weird... ComovingCoordinates = 1 Cameron Matthew Turk wrote: Hi Cameron, Over here it's working for me with 1.5 and trunk: In [2]: pf = load("RD0005-mine/RedshiftOutput0005") In [3]: pf["kpccm"] Out[3]: 7692.3076923076915 Looking at the source, which I am now officially putting on my "clean this up" list, it looks like the comoving units only get set up if the parameter "ComovingCoordinates" is set in the enzo parameter file: http://yt.enzotools.org/browser/trunk/yt/lagos/OutputTypes.py#L323 and then if it is, this routine gets called: http://yt.enzotools.org/browser/trunk/yt/lagos/OutputTypes.py#L340 which sets up all the /h and comoving stuff. I guess the question now is, is yt skipping over the line where it sets those units up, or is it misunderstanding the ComovingCoordinates line in the parameter file? Could you let me know what the value of " pf['ComovingCoordinates'] " is, and what the line in the Enzo parameter file is as well? For me, it looks like: In [5]: pf["ComovingCoordinates"] Out[5]: 1 and the line in the file is: ComovingCoordinates = 1 Thanks, Cameron! -Matt On Mon, Nov 23, 2009 at 10:58 AM, Cameron Hummels <chummels(a)astro.columbia.edu&gt; wrote: Hello everyone:   I upgraded to the new version of yt, and I noticed there was a change in unit designation.  I used to be able to specify units in comoving units of kpc as: "kpccm", but that functionality now appears to be broken.  Does anyone know what the new syntax is for using comoving units? Here is a code example that used to work, but it no longer does in the new version: pf = EnzoStaticOutput(filename) thick_faceon =  10.0/pf['kpccm']                                                                     Thanks!                                                                     Cameron -- Cameron Hummels PhD Candidate, Astronomy Department of Columbia University Public Outreach Director, Astronomy Department of Columbia University NASA IYA New York State Student Ambassador http://outreach.astro.columbia.edu _______________________________________________ yt-users mailing list yt-users(a)lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org _______________________________________________ yt-users mailing list yt-users(a)lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org -- Cameron Hummels PhD Candidate, Astronomy Department of Columbia University Public Outreach Director, Astronomy Department of Columbia University NASA IYA New York State Student Ambassador http://outreach.astro.columbia.edu _______________________________________________ yt-users mailing list yt-users(a)lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org