[R-sig-Geo] apply "raster::aggregate" to multi-layer raster stack, using function that processes values from multiple layers to create a single layer?

Robert J. Hijmans r.hijmans at gmail.com
Sat Jun 21 13:35:13 CEST 2014


How about:

x <- mean(y)


x <- calc(y, mean)


On Fri, Jun 20, 2014 at 2:50 PM, Carlos Carroll
<klamathconservation at gmail.com> wrote:
> When I use "aggregate" (package raster) on a multi-layer stack, with a
> function such as "mean", it returns a second multi-layer stack at the
> aggregated resolution. The function is applied separately to values from
> each layer in turn.
> What I want to do is send the vector/matrix of values extracted across all
> layers to the user-defined function, which returns a single value that
> would then go to form the output, a single layer raster or stack.
> I can do this for a focal function using package spatial.tools, e.g.:
> v<-rasterEngine(w,fun=mean,window_dims = c(15,15,3))  ## for a 3 band stack
> with a window size of 15 by 15.
> But I just need the value at the aggregate resolution, so running a focal
> function takes ~200 times longer than necessary in this case.
> Is it possible to use raster::aggregate or another function to do a similar
> multi-layer operation?
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