2 x-axes

Actually, though, I didn't want to plot 2 different sets of data as in that
example, I want 1 set of data plotted with 2 different x-axis (different units).
Any suggestion on modifying this example to accomplish this?

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid.parasite_axes import SubplotHost

fig = plt.figure(figsize=(10,8))
host = SubplotHost(fig, 111)
fig.add_subplot(host)
parx = host.twiny()

parx.axis["top"].set_visible(False)
offset = 0, -50
new_axisline = parx.get_grid_helper().new_fixed_axis
parx.axis["bottom"] = new_axisline(loc="bottom", axes=parx, offset=offset)
parx.axis["bottom"].label.set_visible(True)

hplt, = host.plot(np.random.rand(100))
p2, = parx.plot(np.linspace(0,20,100), np.random.rand(100)*5.0,
color='green')

plt.show()