Hi all, I've been trying to do some data analysis of an Enzo dataset to extract information about volumes contained with the virial radius of rockstar identified halos. As a test, I've identified the most massive halo and created sphere at that halo position using a bit of code that looks like this: sp = data_ds.sphere([most_massive.quantities['particle_position_x'], most_massive.quantities['particle_position_y'], most_massive.quantities['particle_position_z']], most_massive.quantities['virial_radius']) Then, when I actually try to use the sphere to analyze data or make plots, it seems like there is something screwy going on with the position information, which you can see if you look at the calculations done here: http://paste.yt-project.org/show/5522/ When you look at the "center" based on a calculation of the positions with respect to the domain, you get a different center than the one that just comes of sp.center in "code_length". Specifically, the "code_length" center values all seem to be off from the actual position of the halo by a factor of 1.4: In [98]: sp.center.in_units("kpc")/data_ds.domain_width.in_units("kpc") / sp.center.d Out[98]: YTArray([ 1.40845077, 1.40845077, 1.40845077]) (dimensionless) I'm not sure where this factor is coming from, but it seems to be buried in some sort of unit conversion step somewhere. Thanks, Devin -- Devin W. Silvia NSF Astronomy and Astrophysics Postdoctoral Fellow Department of Physics and Astronomy Michigan State University www.devinsilvia.com _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org