import yt

# load the dataset
ds = yt.load('IsolatedGalaxy/galaxy0030/galaxy0030')

# create our plot
p = yt.ParticlePlot(ds, 'particle_position_x', 'particle_position_y', color='b')

# zoom in a little bit
p.set_width(500, 'kpc')

#save result
p.save()