Question

Can you draw the grid lines in a plot with parasitic axes in matplotlib?

I try this, based on the samples for grids and for parasitic axes, but grid drawing is not performed:

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

fig = plt.figure(1)

host = SubplotHost(fig, 111)
fig.add_subplot(host)

par = host.twinx()

host.set_xlabel("Distance")
host.set_ylabel("Density")
par.set_ylabel("Temperature")

p1, = host.plot([0, 1, 2], [0, 1, 2], label="Density")
p2, = par.plot([0, 1, 2], [0, 3, 2], label="Temperature")

host.axis["left"].label.set_color(p1.get_color())
par.axis["right"].label.set_color(p2.get_color())

host.grid(True)

host.legend()

plt.show()

Answer 1

From the discussion here it looks like this is a bug in the .99 release.

(I’m not sure why it works for doug but no combination of rcParams works for me on version 0.99.1.1-r1.)

From that link the answer is to make a call to:

host.toggle_axisline(False)

What the toggle_axisline does is simply to make the xaxis and yaxis
(which are responsible for drawing ticks, ticklabels, etc in the
mainline mpl) visible again, and make axis[“bottom”] and etc
invisible.

The whole program becomes:

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

fig = plt.figure(1)

host = SubplotHost(fig, 111)
fig.add_subplot(host)

par = host.twinx()

host.set_xlabel("Distance")
host.set_ylabel("Density")
par.set_ylabel("Temperature")

p1, = host.plot([0, 1, 2], [0, 1, 2], label="Density")
p2, = par.plot([0, 1, 2], [0, 3, 2], label="Temperature")

host.axis["left"].label.set_color(p1.get_color())
par.axis["right"].label.set_color(p2.get_color())

host.toggle_axisline(False)
host.grid(True)

host.legend()

plt.show()