Try this:
f <- function(x)
{
sub <- subset(t, select = x)
cbind(Mean = rowMeans(sub, na.rm = T),
Sd = apply(sub, 1, sd, na.rm = T))
#return(sub)
}
do.call(cbind,
lapply(lapply(seq(1, ncol(t), by = ncol(t)/4), seq, l = 3), f))
On Wed, Jun 18, 2008 at 11:17 AM, Daren Tan <[EMAIL PROTECTED]> wrote:
>
> Below example has 4 sets of triplicates, without using for loop and
> iteratively cbind the columns, what is the "R-approach" of generating a
> matrix of 8 columns that are the averages and standard deviations ? The
> average and standard deviation columns should be side by side i.e. A.mean
> A.sd B.mean B.sd C.mean C.sd D.mean D.sd
>
> > t <- matrix(rnorm(120), ncol=12)> (colnames(t) <- paste(rep(LETTERS[1:4],
> each=3), 1:3, sep=".")) [1] "A.1" "A.2" "A.3" "B.1" "B.2" "B.3" "C.1" "C.2"
> "C.3" "D.1" "D.2" "D.3"
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--
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O
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