[R] attaching data.frame/list within a function

[John Fox]

Dear Gardar,

You could use with(); to modify your example slightly,

> a <- "a"
> b <- 5
> foo <- function(x=0, input=list(a=10)) {
+             with(input, {
+                 print(c(a, b, x))
+                 })
+             }
> foo()
[1] 10  5  0
> 

I hope that this helps,
 John 

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Gardar 
> Johannesson
> Sent: Wednesday, April 14, 2004 1:14 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] attaching data.frame/list within a function
> 
> I'm trying to find a good way of attaching a list within a 
> function such that the attached variables (the list's 
> members) precede the global environment (.GlobalEnv) in the 
> search list.  Here is a non-working example using attach(), 
> which hopefully explains better what I'm trying to do:
> 
>  > foo <- function(x=0, input=list(a=10)) {
> +   attach(input)
> +   on.exit(detach(input))
> +   print(search())
> +   print(a)
> + }
>  >
>  > a
> Error: Object "a" not found
>  > foo()  ## this prints out a = 10
> [1] ".GlobalEnv"       "input"            "package:methods"  
> "package:stats"
> [5] "package:graphics" "package:utils"    "Autoloads"        
> "package:base"
> [1] 10
>  >
>  > a <- 0
>  > foo()  ## this prints out a = 0, not a = 10
> [1] ".GlobalEnv"       "input"            "package:methods"  
> "package:stats"
> [5] "package:graphics" "package:utils"    "Autoloads"        
> "package:base"
> [1] 0
>  >
> 
> 
> Thanks,
> 
>                  Gardar
>