Looking for triangulator/interpolator

Travis E. Oliphant oliphant.travis at ieee.org
Sun May 28 05:29:05 CEST 2006


Grant Edwards wrote:
> On 2006-05-27, Travis E. Oliphant <oliphant.travis at ieee.org> wrote:
> 
>> Not that you made a bad choice.  I do wonder, how much of your
>> difficulty was with the interface to the underlying fitpack
>> routines.
> 
> I've no idea.  I had never done anything with splines before,
> so it's quite possible I just wasn't doing things right.  I
> never got it to work at all for non-gridded data (which is what
> I needed).  Since it wasn't stable even for gridded data, I
> more or less gave up.
> 
>> The interface is pretty involved as there are lots of
>> parameter choices to the underlying routine.  It's very
>> possible the interface is broken in some strange way.
> 
> I took a look at underlying Fortran code, but that made my
> dizzy.

Just to finish this thread, I should mention I spent some time yesterday 
looking into the details of the underlying surfit fucntion used by 
bisplrep.  It appears to have difficulties when s=0 is used.  It seems 
to be geared toward smoothing applications where you are trying to fit 
"noisy" scattered data to a smooth function.    There are many warnings 
about choosing s to be too low.

Thus, trying to use bisplrep for interpolation (instead of data 
smoothing) is probably going to be difficult with bisplrep.

We still need a good N-d re-gridding algorithm in SciPy.

-Travis





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