[R] Can you turn a string into a (working) symbol?

[jim holtman]

for the second part use 'assign'

> assign(paste0('a', 'a'), 3)
> aa
[1] 3
>



On Sat, Nov 3, 2012 at 5:31 PM, andrewH <ahoerner at rprogress.org> wrote:
> Dear folks--
>
> Suppose I have an expression that evaluates to a string, and that that
> string, were it not a character vector, would be a symbol.  I would like a
> function, call it doppel(), that will take that expression as an argument
> and produce something that functions exactly like the symbol would have if I
> typed it in the place of the function of the expression.  It should go as
> far along the path to evaluation as the symbol would have, and then stop,
> and be available for subsequent manipulation.  For example, if
>
> aa <- 3.1416
> bb  <- function(x) {x^2}
> r <- 2
> xx <- c("aa", "bb")
>
> out <- doppel(xx[1])*doppel(xx[2])(r)
>
> Then out should be 13.3664
>
> Or similarly, after
> doppel(paste("a",  "a",  sep=''))  <-  3
> aa
>
> typing aa should return 3.
>
> Is there such a function? Can there be?
>
> I thought as.symbol would do this, but it does not.
>> as.symbol (xx[1])*as.symbol (xx[2])(r)
> Error: attempt to apply non-function
>
> Looking forward to hearing from y'all.    --andrewH
>
>
>
>
> --
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>
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-- 
Jim Holtman
Data Munger Guru

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Tell me what you want to do, not how you want to do it.