If it's not already clear, perhaps this slight variation might help
explain what's happening:
b0<-1
b1<-1
x<-1
str2expr<-function(y){eval(parse(text=y))} ## Note change from "x" to "y" here
test1<-"b0+b1*sqrt(x)"
str2expr(test1)
Cheers,
Bert
On Sun, Oct 31, 2010 at 1:58 PM, Duncan Murdoch
<murdoch.duncan at gmail.com> wrote:
On 31/10/2010 4:47 PM, Wu Gong wrote:
Hi Duncan: I'm curious about the environment setting. ?eval says: "If envir is not specified, then the default is parent.frame() (the environment where the call to eval was made). " So what's the difference between set envir=parent.frame() or not?
If you pass parent.frame() as an argument, it will be one level up: it's the parent of the function that calls eval. ?If you leave it at the default, it's the parent of eval, i.e. the function that calls it. Duncan Murdoch
______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Bert Gunter Genentech Nonclinical Biostatistics