[R] Language element manipulation
Duncan Murdoch
dmurdoch at pair.com
Fri Jul 28 05:03:50 CEST 2000
It's hard to do with $. I think you need something like
get('$')(themeas,ameas)
It's easier to use subscripting if themeas is a dataframe:
themeas[,ameas]
Duncan Murdoch
On Thu, 27 Jul 2000 21:43:31 -0500 (CDT), you wrote:
>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
>http://www.consortium-chicago.org/people/sl/sl.html
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>QOTD:
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>>> Sent on 27-Jul-2000 at
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