[R-sig-Geo] Looking for an R package for focal statistics (moving window) within a 3D neighborhood

[Michael Sumner]

Try nabor package.

Cheers, Mike

On Monday, August 31, 2015, Jose Tanago <josetanago at gmail.com> wrote:
> I am writing an algorithm in R for 3D point data sets (centers of voxels),
> read as an R data.frame  with 4 columns (x,y,z values and an attribute).
> They can be big (e.g. millions rows).
>
> I am trying to find any R package that has any function for computing a 3D
> neighborhood (filter or statistics,...). If such funtion{package}  already
> exists it would be great!, but if not, at least any function from a
> non-spatial R-package that could be useful to build an ad-hoc 3D
> neighborhood function might work as well.
>
> Does anyone know a preexisting R package that has a neighborhood
function?,
> or any tips how could be implemented with other packages (customizing or
> building from a more generic package)??
>
> The problem that the function would help: Check the values of the
attribute
> column for all the points within a 3D neighborhood from any point (any
> instance in the data.frame differing less than  "a" value in X,Y,Z,
> coordinates). (i.e. A sort of moving window for a raster but in a 3D
> neighborhood). Then, transform the "cell" or 3D point attribute value, if
a
> condition is fulfilled for any of the 3D neighbors.
>
> If there is no package with a 3D neighborhood function, I though maybe is
> possible to create a custom function that for each instance (point)
> evaluates all others points XYZ  in the data.frame and computing a
> neighborhood attribute value by selecting only the ones within a distance
> in XYZ. But I am not very sure how to make something like this in a
> reasonable way, I guess evaluating all other points xyz will take very
long
> with millions rows.
>
> Thanks a lot for any idea!
>
> Jose Tanago
>
> Lab. of Remote Sensing, Wageningen University
>
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>
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-- 
Michael Sumner
Software and Database Engineer
Australian Antarctic Division
Hobart, Australia
e-mail: mdsumner at gmail.com

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