Three bars with three y-axes in matplotlib python

Question

I'd like to use three bars with three y-axes in matplotlib python.

I use two bars with two y-axes, everything is ok Ref. ,

but once added the third one is not good.

I'd like to add the third scale using black color.

Please your help.

width = 0.25
fig, ax1 = plt.subplots()
ind = np.arange(len(r2_score1))
print 'r2_score1', r2_score1
rects1 = ax1.bar(ind, r2_score1, width, color = 'b')
ax1.set_xticks(ind+width)
ax1.set_xticklabels(names, fontsize=14)
ax1.set_ylabel('r2_score', color='b')
for tl in ax1.get_yticklabels():
    tl.set_color('b')


ax2 = ax1.twinx()
rects2 = ax2.bar(ind + width, time_model, width, color = 'r')
ax2.set_ylabel('Time (s)', color='r')
for tl in ax2.get_yticklabels():
   tl.set_color('r')


ax3 = ax2.twinx()
rects3 = ax3.bar(ind + width+ width, rmse, width, color = 'k')
ax3.set_ylabel('rmse', color='k')
for tl in ax3.get_yticklabels():
   tl.set_color('k')

Maybe this helps? https://stackoverflow.com/questions/35398649/plotting-and-color-coding-multiple-y-axes — Maria, Jan 19 '21 at 09:55
This is well explained in the [parasite axis demo](https://matplotlib.org/3.3.1/gallery/axisartist/demo_parasite_axes2.html) of matplotlib - they even offer [a second version](https://matplotlib.org/3.3.1/gallery/ticks_and_spines/multiple_yaxis_with_spines.html) to address this problem. — Mr. T, Jan 19 '21 at 12:43

score 0 · Accepted Answer · answered Jan 20 '21 at 06:04

From your links, it solved it now, as

width = 0.25
from mpl_toolkits.axes_grid1 import host_subplot
from mpl_toolkits import axisartist
host = host_subplot(111, axes_class=axisartist.Axes)
plt.subplots_adjust(right=0.75)

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

par2.axis["right"] = par2.new_fixed_axis(loc="right", offset=(80, 0))

par1.axis["right"].toggle(all=True)
par2.axis["right"].toggle(all=True)

ind = np.arange(len(r2_score1))
print 'r2_score1', r2_score1
rects1 = host.bar(ind, r2_score1, width, color = 'b')
host.set_xticks(ind+width)
host.set_xticklabels(names, fontsize=20)
for tl in host.get_yticklabels():
    tl.set_color('b')


print 'time_model', time_model
rects2 = par1.bar(ind + width, rmse, width, color = 'k')
for tl in par1.get_yticklabels():
   tl.set_color('k')




rects3 = par2.bar(ind + width+ width,  time_model, width, color = 'r')
for tl in par2.get_yticklabels():
   tl.set_color('r')

host.set_xticklabels(names, fontsize=20)
host.set_ylabel('$R^2$ Score',  color='b')
par1.set_ylabel('RMSE',  color='k')
par2.set_ylabel('Time (ms)',  color='r')


host.legend()
plt.show()

Thanks again.

Three bars with three y-axes in matplotlib python

1 Answers1