Re: [Matplotlib-users] Contouring a large set of ungridded data

[Robert K. <rk...@uc...>]

John Hunter wrote:
>>>>>>"Jeff" == Jeff Whitaker <js...@fa...> writes:
> 
>     Jeff> John: I've now a got a toolkit built with no CDAT code in
>     Jeff> it, using the NCAR natgrid library which is GPL. I've done a
>     Jeff> fair amount of searching and haven't found anything else
>     Jeff> that provides similar functionality with better
>     Jeff> (i.e. BSD-like) licensing.  The prototype natgrid toolkit is
>     Jeff> at /Public/jsw/natgrid-0.1.tar.gz if you'd like to take a
>     Jeff> look.  All it does is provide a single function, griddata,
>     Jeff> which works much the same as the matlab version.  I'm ready
>     Jeff> to put it CVS if you give the go ahead.
> 
> I'm hesitant to include any GPL code even as a toolkit.  For one
> thing, it decreases the impetus for someone to provide a version that
> is compatible with the mpl license.  Perhaps this would be better
> placed on the wiki?
> 
> I know that VTK is BSD compatible and has delaunay triangulation, but
> obviously it is impractical to try and pull anything out of VTK.  I
> think the qhull license is less restrictive:
> http://www.qhull.org/COPYING.txt.  In short, I wonder if we have
> really exhausted all the possibilities.  Something from netlib?
> There was a recent thread on scipy in which Eric Jones posted a link
> to some code (FORTRAN I believe) that does something analogous.  It
> would be nice to have something in C/C++ and something that is BSD
> compatible.  Perhaps I'm dreaming.

I've spent time looking. Everything that I've found with a BSD-like
license isn't a very good library. Global variables are usually the
culprit. qhull, for example, is a real PITA in this regard. The code
that Eric found was from ACM TOMS, I believe, and so I'd question its
license.

In any case, natgrid isn't Delaunay triangulation, but natural neighbors
interpolation which is better (and probably state of the art for these
kinds of graphics). It might be easiest to contact Dave Watson and ask
if we can distribute his code in matplotlib under matplotlib's license.
I can't find any contact information for him, however.

-- 
Robert Kern
rk...@uc...

"In the fields of hell where the grass grows high
 Are the graves of dreams allowed to die."
  -- Richard Harter