[R] question about deparse(substitute(...))

[William Dunlap]

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Sean Zhang
> Sent: Thursday, January 13, 2011 4:37 PM
> To: r-help at r-project.org
> Subject: [R] question about deparse(substitute(...))
> 
> Dear R helpers:
> 
> I like to apply deparse(substitute()) on multiple arguments 
> to collect the
> names of the arguments into a character vector.
> I used function test.fun as below. it works when there is 
> only one input
> argument. but it does not work for multiple arguements. can 
> someone kindly
> help?
> 
> test.fun <- function(...){deparse(substitute(...))}
> test.fun(x) #this works
> test.fun(x,y,z) # I like c('x','y','z') be the output, but 
> cannot get it.

One way is:
   > f <- function(...) lapply(substitute(placeholderFunction(...))[-1],
deparse)
   > f(x, log(y), (function(a){a+a^2/2+a^3/6})(z))
   [[1]]
   [1] "x"

   [[2]]
   [1] "log(y)"

   [[3]]
   [1] "(function(a) {"       
   [2] "    a + a^2/2 + a^3/6"
   [3] "})(z)"                

Use paste(collapse="\n",s) or s[1] on
deparse's output if you require one
string per input.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com  

> 
> Thanks in advance.
> 
> -Sean
> 
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> 
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