import yt

ds = yt.load("GasSloshing/sloshing_nomag2_hdf5_plt_cnt_0150")

print ds.domain_left_edge
print ds.domain_right_edge

# default width figures out units properly
yt.SlicePlot(ds, 'x', 'density')

# use domain_*_edge (units of code_length) to specify width of Slice; plot has code_length instead of ds.length_unit
w = (ds.domain_right_edge[1], ds.domain_right_edge[2])
yt.SlicePlot(ds, 'x', 'density', width=w)

# use a combination of domain_right_edge and ds.quan really screws up
w = (ds.domain_right_edge[1], ds.quan(1, 'Mpc'))
yt.SlicePlot(ds, 'x', 'density', width=w)