[R] Application of "merge" and "within"

[Santosh]

Dear Rxperts!

Is there a way to compute relative values.. using within().. function?

Any assistance/suggestions are highly welcome!!
Thanks again,
Santosh...
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A sample dataset and the computation "outside" within()  function is shown..

q <- data.frame(GL = rep(paste("G",1:3,sep = ""),each = 50),
                G  = rep(1:3,each = 50),
                D = rep(paste("D",1:5,sep = ""),each = 30),
                a = rep(1:15,each = 10),
                t = rep(seq(10),15),
                b = round(runif(150,10,20)))
r <- subset(q,!duplicated(paste(G,a)),sel=c(G,a,b))
names(r)[3] <- "bl"
s <- merge(q,r)
 s$db <- s$b-s$bl

> head(s,5)
    G  a GL  D  t  b bl db
1   1  1 G1 D1  1 13 13  0
2   1  1 G1 D1  2 16 13  3
3   1  1 G1 D1  3 19 13  6
4   1  1 G1 D1  4 12 13 -1
5   1  1 G1 D1  5 19 13  6

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