Hi Amit,
I am with you 100% of the way. We should use an existing open source
Delaunay triangulator, and my preference is for QHull as well.
"Improved Delaunay triangulator" is on my matplotlib todo list, albeit it
quite a long way from the top. I don't tend to use the existing code as I
usually specify my own triangulations, so I have never seen anything quite
as embarrassing as issue #1809. Perhaps I need to bump it up my priority
list.
If I come up with a possible solution as a PR, would you be prepared to
help test it? You seem to have quite a few examples that don't work under
the existing code and would be very useful for demonstrating if the
improved code is indeed an improvement.
Ian
On 5 March 2013 23:08, Amit Aronovitch <aronovi...@gmail.com> wrote:
> Dear MPL-devs,
>
> Currently, matplotlib does Delaunay triangulation using a special
> purpose module written in C++ (if I'm not mistaken, it was originally
> forked off from some SciKit and wrapped into a Python module).
> Some people (here and on github issues) had suggested it might need some
> rewrites/modification.
> In particular I was wondering if we should continue maintaining it here
> or maybe switch to using some external library.
>
> Since triangulation is not a plotting-specific problem, and some free
> libraries are available for solving it, we might actually benefit in
> terms of efficiency and robustness.
>
> Specifically, I had suggested QHull, which is used by scipy (note that
> now there is also a stand-alone python interface:
> https://pypi.python.org/pypi/pyhull - I did not check that out yet).
> @dmcdougall had suggested Jonathan Shewchuk's triangle library (we
> should check the license though - I think it is "for non-commercial
> use", unlike mpl). There are also other alternatives.
>
> On the other hand, there's the issue of minimizing external
> dependencies. I think @ianthomas23 had once mentioned that he is happy
> with having Delaunay code reside in mpl (and, of course, "maintainable"
> is whatever is most convenient for the maintainers).
>
> I apologize for suggesting more tasks without contributing time to work
> on them. Just thought that since I finally sat down to report issue
> #1809 (which seems to be a particularly slippery bug in the code
> mentioned above), it might be a good time to discuss this topic again.
>
> thanks,
>
> Amit Aronovitch
>
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