Dear All,

I am very new in YT 3.3's HaloCatalog functionality. With the following piece of code, I am able to get paerical mass and virial radius. 

import yt
from yt.analysis_modules.halo_analysis.api import HaloCatalog
data_ds = yt.load('/run/media/john/Seagate_Expansion_Drive/cosmo-sim_20/RD0057/RedshiftOutput0057')
hc = HaloCatalog(data_ds=data_ds, finder_method='hop')
ad = hc.halos_ds.all_data()
pm = ad['particle_mass'][:]
vr = ad['virial_radius'][:]

I would like to calculate the center of mass of the halo. I tried with the following line
com = ad['center_of_mass'][:]
since like virial_radius()center_of_mass() was available in YT2.6.
But this is not working. 

Could you please suggest me how to calculate the center of mass of a halo in yt 3.3.3 ?

Reju Sam John