def read_snap(gal, snap, snapmin, bh, centerarray, rvirarray, centertype):
if centertype == 'rockstar':
padding = 95 - len(centerarray)
center = centerarray[snap - padding]
rvir = rvirarray[snap - padding]
if centertype == 'gtrace':
center = centerarray[snap - snapmin + 1]
rvir = rvirarray[snap - snapmin + 1]
s = pygad.Snap('/Volumes/Happy/Choi16_Fiducial/Fiducial_' + str(bh) +
'/m0' + str(gal).zfill(3) + '/snap_m0' + str(gal).zfill(3) +
'_sf_x_2x_' + str(snap).zfill(3),
load_double_prec=True)
s.to_physical_units()
pygad.Translation(-center).apply(s)
vel_center = pygad.analysis.mass_weighted_mean(
s.stars[pygad.BallMask('1 kpc',
center=pygad.UnitArr([0.0, 0.0, 0.0], 'kpc'))],
'vel')
s['vel'] -= vel_center
return s
center = centerarray[snap - snapmin + 1]
#this is the pygad function to read in the snapshot
s = pygad.Snap('/Volumes/G-RAID/Choi16_Fiducial/Fiducial_MrAGN/m0' +
str(gal).zfill(3) + '/snap_m0' + str(gal).zfill(3) +
'_sf_x_2x_' + str(snap).zfill(3),
load_double_prec=True)
#this converts all of the quantities with factors of the hubble constant and the scale factor to physical units
s.to_physical_units()
#Here we center the positions and velocities on the center that we established above
pygad.Translation(-center).apply(s)
vel_center = pygad.analysis.mass_weighted_mean(
s.stars[pygad.BallMask('1 kpc',
center=pygad.UnitArr([0.0, 0.0, 0.0], 'kpc'))],
'vel')
s['vel'] -= vel_center
#------------------------------------------------------------------------------
#the reason for the dotted lines (and the reason that I loaded in the virial radius and the centers separately), is because everything between the two dotted lines can be done just by using a function that I wrote called read_snap. I still wanted you to see how pygad natively reads snapshots, though. In order to use the function, just put read_snap.py in the same directory as your code
#Everything between the dotted lines can be achieved by importing read_snap at the beginning of the file and then in place of the code within the dotted lines:
s = read_snap.read_snap(gal, snap, snapmin, 'MrAGN', centerarray, rvirarray,