[Matplotlib-users] Contour Plotting of Varied Data on a Shape

Ian Thomas wrote:

Chris Barker wrote:

I think it would be great to have in MPL.

What code are you using for the triangulation? Does it do constrained
delauney?

My code only does the contouring; you have to input the triangulation.
In the examples included with the code I used matplotlib.delaunay to
do the triangulations so as not to reinvent the wheel.

To include it in MPL, I would need to improve it somewhat (there are a
couple of known bugs and insufficient documentation) and there would
need to be a discussion of the API. At the moment I am using

    tricontour(x, y, triangulation_indices, z, optional_mask)

followed by the usual contour args (N or V) and kwargs. Is this OK?
I've also written utility plotting functions triplot, trifill and
tripcolor; are these wanted?

In terms of implementation, at the python level I have a TriContourSet
class which is the same as the existing ContourSet apart from a few
lines that deal with input arguments and calling the appropriate
underlying C++ code. Ideally it would be sensible to refactor the
common python code into a new class (BaseContourSet?) and have
relatively thin derived ContourSet and TriContourSet classes. But I'm
not sure you'd like a relatively new mpl contributor to change such
important code...

Ian,

As the person who fixed major bugs in cntr.c, you have wizard status, so go ahead! I have no objection to some refactoring, so long as everything works in the end, and is no more difficult to read and maintain than what is there now--which I am sure could be improved even without the Tri additions.

What sort of timeline do you have in mind?

One possibility would be to develop the tri* functionality at least initially as a module in lib/mpl_toolkits, like axes_grid and mplot3d; or in a module in lib/matplotlib. This could still take advantage of refactoring in contour.py. An advantage is that it would consolidate the triangle functionality so it would be easier to find, track, and document.

I copied this reply to the devel list--let's continue there as needed.

Eric

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Ian