matplotlib: adding padding/offset to polar plots tick labels

axis-labels, label, matplotlib, radial

Solution

First of all; seeing as how you have specified the `figsize` to be (2,2) and having the `ax` occupy 80 % of both the width and height, you have very little space left over to pad the ticklabels. This could cause the ticklabels to be "cut off" at the figure's egdes. This can easily be "fixed" by either

- Specifying bigger `figsize`

- Make the `ax` occupy less space on the (2,2) sized figure

- Use smaller fontsize for the ticklabels

or any combination of these. Another, in my opinion better, solution to this "problem" is to use a subplot rather than specifying the `Axes`'s bounds;

ax = fig.add_subplot(111, polar=True, axisbg='#d5de9c')

as this makes it possible to use the method `tight_layout()` which automatically configures the figure layout to nicely include all elements.

Then over to the real problem at hand; the padding. On a `PolarAxes` you can set, among other things, the radial placement of the theta-ticks. This is done by specifying the fraction of the polar axes radius where you want the ticklabels to be placed as an argument to the `frac` parameter of the `PolarAxes`'s `set_thetagrids()` method. The argument should be a fraction of the axes' radius where you want the ticklabels placed. I.e. for `frac` < 1 the ticklabels will be placed inside the axes, while for `frac` > 1 they will be placed outside the axes.

Your code could then be something like this:

import numpy as np
from matplotlib.pyplot import figure, show, grid, tight_layout
# make a square figure
fig = figure(figsize=(2, 2))
ax = fig.add_subplot(111, polar=True, axisbg='#d5de9c')
ax.set_yticklabels([])

r = np.arange(0, 3.0, 0.01)
theta = 2*np.pi*r
ax.plot(theta, r, color='#ee8d18', lw=3)
ax.set_rmax(2.0)

# tick locations
thetaticks = np.arange(0,360,45)

# set ticklabels location at 1.3 times the axes' radius
ax.set_thetagrids(thetaticks, frac=1.3)

tight_layout()

show()

You should try different values for `frac` to find a value that is best suited for your needs.

If you don't specify a value to the parameter `frac` as above, i.e. `frac` has default value `None`, the code outputs a plot as below. Notice how the radius of the plot is bigger, as the ticklabels don't "occupy as much space" as in the example above.

Problem

Original source