Change color of parasite axis in matplotlib

Question

I want to change color of parasitic axis.

Base code is example from http://matplotlib.org/examples/axes_grid/demo_parasite_axes2.html

I just add

par1.spines['right'].set_color("red")

to change the color (according to https://stackoverflow.com/a/12059429/716469). But it doesn't work.

The full code:

from mpl_toolkits.axes_grid1 import host_subplot
import mpl_toolkits.axisartist as AA
import matplotlib.pyplot as plt

host = host_subplot(111, axes_class=AA.Axes)
plt.subplots_adjust(right=0.75)

par1 = host.twinx()
par2 = host.twinx()

offset = 60
new_fixed_axis = par2.get_grid_helper().new_fixed_axis
par2.axis["right"] = new_fixed_axis(loc="right",
                                    axes=par2,
                                    offset=(offset, 0))

par2.axis["right"].toggle(all=True)

host.set_xlim(0, 2)
host.set_ylim(0, 2)

host.set_xlabel("Distance")
host.set_ylabel("Density")
par1.set_ylabel("Temperature")
par2.set_ylabel("Velocity")

p1, = host.plot([0, 1, 2], [0, 1, 2], label="Density")
p2, = par1.plot([0, 1, 2], [0, 3, 2], label="Temperature")
p3, = par2.plot([0, 1, 2], [50, 30, 15], label="Velocity")

par1.set_ylim(0, 4)
par2.set_ylim(1, 65)

host.legend()

host.axis["left"].label.set_color(p1.get_color())
par1.axis["right"].label.set_color(p2.get_color())
par2.axis["right"].label.set_color(p3.get_color())

# Why doesn't work?
par1.spines['right'].set_color("red")

plt.draw()
plt.show()

I use matplotlib 2.0.0

Answer 1

The host_subplot creates an instance of mpl_toolkits.axisartist.axis_artist.AxisArtist which is not the same as a normal axes.

You therefore need to set the attributes of the axis just like you do with the label,

host.axis["right"].line.set_color(p2.get_color())
par1.axis["right"].major_ticks.set_color(p2.get_color())
par1.axis["right"].major_ticklabels.set_color(p2.get_color())

par2.axis["right"].line.set_color(p3.get_color())
par2.axis["right"].major_ticks.set_color(p3.get_color())
par2.axis["right"].major_ticklabels.set_color(p3.get_color())