import numpy as np
import pyvista as pv
from scipy.spatial import Delaunay

import matplotlib.pyplot as plt
from matplotlib.tri import Triangulation

# create disk mesh
disk = pv.Disc(center=(0.,0.,0.), inner=1.22, outer=2.22, normal=(0.,0.,1.), r_res=64, c_res=360)
points = disk.points[:,:2]

# create sample data
data = np.exp( - np.power((np.linalg.norm(points, axis=1) - 1.72) / 0.25, 2.) / 2.)

# triangulate
tess = Delaunay(points)
r = np.linalg.norm(points, axis=1)
theta = np.arctan2(points[:,1], points[:,0])
triang = Triangulation(x=theta, y=r, triangles=tess.simplices)

fig, ax = plt.subplots(1, 2, subplot_kw={'projection': 'polar'})
ax[0].tripcolor(triang, data, shading='gouraud')
ax[0].set_title('gouraud')
ax[1].tripcolor(triang, data, shading='flat')
ax[1].set_title('flat')
plt.show()