Python: Matplotlib Patches and Contour Plots

Question

Is there a way to make the filling of a circle transparent when using the PatchCollection? I plotted a circle, and I tried setting the facecolor to 'none', but it is covering the contour map that it is plotted on top of. I would like to see the outline of the circle with the contouring remaining visible behind it.

The stereonet was plotted using the mplstereonet-0.2 third-party software. Here is the part of the script where the image is plotted:

hold(True)



fig, ax = plt.subplots(subplot_kw = dict(projection = 'stereonet')) # Schmidt by default

cax = ax.density_contourf(strike, dip, measurement = 'poles')

ax.pole(strike, dip, 'k^', markersize = 3)
ax.grid(True)


patches = []
circle = Circle((0, 0), 0.5, facecolor = 'none', fill = False)
patches.append(circle)
p = PatchCollection(patches)
ax.add_collection(p)

cbar = fig.colorbar(cax, cmap = cm)
cbar.set_clim(0, 25)

enter image description here

user1620716 · Accepted Answer · 2012-11-23 15:59:29Z

3

I solved the problem, but thank you to anyone that was possibly looking into this.

The solution:

    p = PatchCollection(patches, match_original = True)

This will make it so that the contour is seen behind the shape.

enter image description here

answered Nov 23, 2012 at 15:59

user1620716

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3 Comments

Rutger Kassies Over a year ago

I was just about to respond. My comment would be that if you only plot 1 circle, avoid the whole PatchColection and add it direcly with: ax.add_artist(circle)

jorgeca Over a year ago

Nice. I was going to suggest using ax.add_patch(circle) which works fine (if you only have one patch there's no need to use a PatchCollection). Though, you should have really provided a minimal working example in your question.

Joe Kington Over a year ago

Just FYI, you can also specify facecolor='none' when creating the PatchCollection (or use p.set_facecolor). The reason that the default isn't to match the original patch when making a collection is that collections are commonly used to either speed up drawing of a bunch of almost identical artists or map some attribute such as facecolor to another scalar (e.g. color by z). (On another side note, I didn't even know the match_original option existed. That's handy!) As everyone else mentioned, for a single circle, just adding it directly is easier. Good luck!

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