[R] Avoid using "eval" in a neat way

[Ista Zahn]

This has been discussed extensively, on this list as well as
elsewhere. I suggest doing a web search, read up on the issue, and
post back here only if you have specific questions that are not
answered already.

Best,
Ista

On Sat, Feb 1, 2014 at 11:40 AM, Hai Qian <hqian at gopivotal.com> wrote:
> I know using eval is not optimal and maybe bad, but how to avoid using eval
> in the following example
>
> func1 <- function(dat, eval.this) {
>     eval(parse(text = paste0("with(dat, ", eval.this, ")")))
> }
>
> dat <- data.frame(x = 1:2, y = 2:3)
>
> func1(dat, "x*2+y")
>
> func1(dat, "sin(x)*cos(y)")
>
> Here eval.this is a string that contains whatever the user wants to
> evaluate. I wonder whether there is a neat way to avoid using eval in this
> case? So far I have not figured out a way to do this.
>
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>
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