# External routines we need.
import g3read as g3
import matplotlib as mpl
mpl.use('TkAgg')
import matplotlib.pyplot as plt

# Read the data from the snapshot.
filename = 'snap_144'
f = g3.GadgetFile(filename)
pos = f.read_new("POS ", 0)

# Set up the figure and axis ranges.
fig = plt.figure()
ax = plt.axes(xlim=(0, 48000), ylim=(0, 48000))
ax.set_aspect('equal', adjustable='box')

# Plot the positions.
point = ax.plot(pos[:,0], pos[:,1], '.', markersize=0.1)

# Show the plot.
plt.show()