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

[Christian Levers]

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
web:    http://www.geographie.hu-berlin.de