Hi Cameron,
> I have a field where some of the values are NaN.
> I would like to remove these missing values by changing them
> to their nearest neighbor (or some other algorithm).
> Is there a visad way of doing this?
> Or do I have to define some sort of custom interpolation?
It all depends on how dense your missing points are. If
most points are missing, then you could treat the non-missing
points as samples of an IrregularSet. The IrregularSet
constructor will invoke a Delaunay algorithm, which will be
quite slow. Then you can resample that IrregularSet back
to your original GriddedSet. A faster way (still for most
points missing) would be to use an objective analysis
algorithm. We've got some Fortran for this at:
ftp://hyde.ssec.wisc.edu/pub/misc/fbarn.f
Also, I believe your advisor James Kelly is an expert on
objective analysis.
If your missing points are sparse, then you should be
probably just use a simple spot noise filter. For example,
replace each missing point by the average of adjacent
non-missing points.
Cheers,
Bill
----------------------------------------------------------
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI 53706
hibbard@xxxxxxxxxxxxxxxxx 608-263-4427 fax: 608-263-6738
http://www.ssec.wisc.edu/~billh/vis.html
