Set mask for matplotlib tricontourf

Question

I have some numpy array containing data that I would visualize on a 2D grid. Some of the data is unphysical and I would like to mask this data. However, I could not figure o

Answer 1

Here comes the trick. I need to collect the indices of triangles (which are indices into z!), evaluate whether they are good or not and then accept only the triangles for that at least one corner is valid (reducing the dimension from (ntri, 3) to ntri

triang = tr.Triangulation(x, y)
mask = np.all(np.where(isbad[triang.triangles], True, False), axis=1)
triang.set_mask(mask)
colplt = mp.tricontourf(triang, z)
mp.colorbar()

Inspired by this link: http://matplotlib.org/examples/pylab_examples/tripcolor_demo.html

Answer 2

wsj's answer didn't work for me since it didn't remove certain masked points (I think when not all of the nodes where bad).

This solution did:

z[isbad] = numpy.NaN
z = numpy.ma.masked_invalid(z)
vmin, vmax = z.min(), z.max()
z = z.filled(fill_value=-999)

levels = numpy.linspace(vmin, vmax, n_points)
plt.tricontourf(x, y, z, levels=levels)