[R-sig-Geo] raster package - zonal - standard deviations

[Rafael Wüest]

Hi Christian

What version of raster do you use. Using my installation of raster (version 2.0-12), 'sd' as a function in zonal works fine (see example below).

r <- raster(ncols=10, nrows=10)
r[] <- runif(ncell(r)) * 1:ncell(r)
z <- r
z[] <- rep(1:5, each=20)
zonal(r, z, 'sd')
     zone      "sd"
[1,]    1  4.894058
[2,]    2  9.216353
[3,]    3 14.144341
[4,]    4 19.973913
[5,]    5 27.934773

I guess updating the raster package will solve the problem.

Best,
Rafael

On 02.11.2012, at 18:35, Christian Levers wrote:

> Hello,
> 
> I am using the raster package to calculate zonal statistics for my stack of ca. 50 rasters (each raster is about 33 mio. pixels) and I am wondering if there is a simple way to calculate standard deviations for the zones since "sd" is not implemented in the presets for the "stat" argument. If not, I guess defining a function which calculates std.dev is the easiest solution.
> 
> Thanks in advance and a nice weekend,
> Christian
> 
> -- 
> MSc Geogr. Christian Levers
> Doctoral Researcher
> 
> Biogeography & Conservation Biology
> Geography Department | Humboldt-Universitaet zu Berlin
> 
> eMail:  christian.levers at geo.hu-berlin.de
> phone:  +49 (0) 30 2093 9341
> fax:    +49 (0) 30 2093 6848
> mail:   Unter den Linden 6 | 10099 Berlin | Germany
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> 
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--
Rafael Wüest
Swiss Federal Research Institute WSL
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