[R] Apply functions along "layers" of a data matrix

Paul Hiemstra paul.hiemstra at knmi.nl
Fri Nov 18 14:25:59 CET 2011


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



More information about the R-help mailing list