Apply functions along "layers" of a data matrix
On 11/18/2011 01:05 PM, saschaview at gmail.com wrote:
daf <- data.frame(
'id' = rep(1:5, 3),
matrix(1:60, nrow=15, dimnames=list( NULL, paste('v', 1:4, sep='') )),
rep = rep(1:3, each=5)
)
Hi, This seems like a job for plyr! library(plyr) ddply(daf, .(rep), summarise, mn = mean(v1)) hope this helps, Paul
Paul Hiemstra, Ph.D. Global Climate Division Royal Netherlands Meteorological Institute (KNMI) Wilhelminalaan 10 | 3732 GK | De Bilt | Kamer B 3.39 P.O. Box 201 | 3730 AE | De Bilt tel: +31 30 2206 494 http://intamap.geo.uu.nl/~paul http://nl.linkedin.com/pub/paul-hiemstra/20/30b/770