API for astropy.units aware plotting

unit_plot_api.py

# API for unit-aware plotting
theta1 = np.random.uniform(0., 360., size=100)*u.degree
phi1 = np.random.uniform(-90., 90., size=100)*u.degree

theta2 = np.random.uniform(0., 24., size=50)*u.hourangle
phi2 = np.random.uniform(-90., 90, size=50)*u.degree

ax = fig.add_subplot(111)
ax.plot(theta1, phi1)
ax.plot(theta2, phi2)
# default units are degrees, because those were plotted first

# can change units like this
ax.set_xunits(u.hourangle)
ax.set_yunits(u.radian)