
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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