Python/Matplotlib Inverse Fill of Polar Plot Polygon

Question

Currently I have the following script that generates a polar plot of azimuth/radius data. "R1" is simple a list of values of [azimuth, inclination] derived from a table in ArcGIS.

import matplotlib.pyplot as plt
import numpy as np 

for(a,r) in R1:
    angles.append(a)
    radius.append(90-r)
theta = np.radians(angles)
r = radius

ax = plt.subplot(111,polar=True)
ax.plot(theta, r, color='black', ls='-', linewidth=1)
ax.fill(theta,r,'0.75') ## should I use ax.fill_betweenx() ?
ax.set_theta_zero_location('N')
ax.set_theta_direction(-1)
ax.set_rmax(90)
ax.set_rmin(0)
ax.set_yticks(range(0,90,10))
yLabel=['90','','','60','','','30','','','']
ax.set_yticklabels(yLabel)
ax.grid(True)
plt.show()

At the moment this creates the following plot:

How can I "invert" the fill so that what is filled with gray will be white, and what is white will be gray?

I have tried ax.fill_betweenx(theta,90,r,color='0.75') and that didn't work. I have been battling with this for some time now to no avail.

ANY help or suggestions are greatly appreciated!

If there is any way I can make this clearer, please let me know in the comments.

Answer 1

Depending on what you want to do with this later, the quickest way is to simply make the background gray and the fill white:

import matplotlib.pyplot as plt
import numpy as np
ax = plt.subplot(111, polar=True)

theta = np.linspace(0, 2*np.pi, 100)
r = 2 + np.sin(theta * 2)
ax.patch.set_facecolor('0.5')
ax.plot(theta, r, color='black', ls='-', linewidth=1)
ax.fill(theta,r,'w')
plt.show()
plt.draw() # just to be safe!