CODEWITHSUNDEEP
pythonmatplotlib
JonathanU
JonathanU

Reputation: 111

Adding a colorbar to a pcolormesh with polar projection

I am trying to add a colorbar to a pcolormesh plot with polar projection. The code works fine if I don't specify a polar projection. With polar projection specified, a tiny plot results, and the colorbar is absent. Am I doing something stupid, or is this a bug? I am using matplotlib 1.3.1 on Fedora 20.

import matplotlib.pyplot as plot
import mpl_toolkits.axes_grid1 as axes_grid1
import numpy as np

t = np.linspace(0.0, 2.0 * np.pi, 360)
r = np.linspace(0,100,200)
rg, tg = np.meshgrid(r,t)
c = rg * np.sin(tg)

# If I remove the projection="polar" argument here the 
ax = plot.subplot2grid((1, 1), (0, 0), projection="polar", aspect=1.)
im = ax.pcolormesh(t, r, c.T)
divider = axes_grid1.make_axes_locatable(ax)
cax = divider.append_axes("right", size="5%", pad=0.05)
plot.colorbar(im, cax=cax)
plot.show()

Upvotes: 7

Views: 5351

Answers (1)

CT Zhu
CT Zhu

Reputation: 54340

In the way you are doing it, the cax axis is actually in polar projection. You can verify it by: 

cax = divider.append_axes("right", size="200%", pad=0.5)
#plot.colorbar(im, cax=cax)
cax.pcolormesh(t, r, c.T)

While this might be a bug, I think a cleaner way to achieve it might be to use GridSpec:

gs = gridspec.GridSpec(1, 2,
                       width_ratios=[10,1],
                       )

ax1 = plt.subplot(gs[0], projection="polar", aspect=1.)
ax2 = plt.subplot(gs[1])

t = np.linspace(0.0, 2.0 * np.pi, 360)
r = np.linspace(0,100,200)
rg, tg = np.meshgrid(r,t)
c = rg * np.sin(tg)

im = ax1.pcolormesh(t, r, c.T)
plot.colorbar(im, cax=ax2)

enter image description here

Upvotes: 6

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