[R-sig-Geo] how to find cells in a raster

[Robert J. Hijmans]

Roman,

Perhaps you can make a RasterLayer with the cell numbers and then use
xyValues with a buffer

r <- raster(original.raser)
r[] <- 1:ncell(r)
xyValues(r, points, buffer=?)

Robert

On Wed, Jun 23, 2010 at 7:02 AM, Roman Luštrik <roman.lustrik at gmail.com> wrote:
> Dear list,
>
> I'm trying to find cells in a RasterLayer object. Specifically, I'm trying
> to find all cells within a radius from a pre-defined point. When I have cell
> numbers or coordinates, I can calculate their distance from the
> aforementioned pre-defined point.
> So far, I've been overlaying a polygon and extracting cell numbers with
> polygonValues(), however, this method seems to be somewhat slow (especially
> on larger rasters). I've benchmarked it and it is approximately as fast as
> if I used distanceFromPoints(), which calculates distances for all cells in
> a raster. Is there a faster way of finding these cells?
>
> Cheers,
> Roman
>
>
> --
> In God we trust, all others bring data.
>
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