[R] Language element manipulation

[Stuart Luppescu]

I am very confused about this. I want to convert a string to a name so I can
use it to extract an element of a data frame using `$'. Here is my
(non-working) code:

do.graph <- function (meas)
  {
    fn <- paste("a", meas, ".dat", sep='')
    themeas <- read.table(fn, header=F)
    ameas <- as.name(paste("a", meas, sep=''))
    names(themeas) <- c("xpos", paste("a", meas, sep=''))
    meassum <- summary(themeas$ameas[themeas$xpos==1])
   ...
   }
So, when this function is called with the argument ``infl'' the second column
will be named ``ainfl''. In the last line I want to extract the column called
``ainfl'' from the data frame ``themeas''. But this is what happens:

> themeas$ameas
NULL

Just grabbing at straws here:

 themeas$eval(ameas)
Error: attempt to apply non-function

Can someone wise me up about this?
______________________________________________________________________
Stuart Luppescu         -=-=-  University of Chicago
ºÍʸ ¤ÈÃÒÆàÈþ¤ÎÉã(EUC)  -=-=-  s-luppescu at uchicago.edu
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>> Sent on 27-Jul-2000 at 
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