[R] problem with substitute

[R. Heberto Ghezzo]

Hello, I have a data base with variables pasthma,kasthma,sex,etc.
I wrote a program to compute the Kappa statistic between pasthma and
kasthma.
Actually "did the child had asthma" answered by the parents and by the
child.
kappa <- function(x) {
  r <- paste("p",evaluate(x),sep="")
 c <- paste("k",evaluate(x),sep="")
 a <- table(r,c)
...
}
If I call "kappa(asthma)" it works as expected ( "by me"). But if I call

"kappa(asthma[sex==1])" it does not because of evaluate
 r is "p["  "pasthma"  "psex==1" and I intended to be "pasthma[sex==1]"
Is there a way around, or I am using the wrong approach?
Thanks for any help
.
Heberto Ghezzo Ph.D.
McGill University
Montreal - Canada


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