[R] Deparsing '...'

[Peter Dalgaard]

Matthew Dowle <mdowle at concordiafunds.com> writes:

> That's even neater.  But when its called from within another function, this
> happens, see below.  I was planning to call f something like 'getdots' and
> use it in several functions that need to do this.
> 
> > f <- function(...) as.character(match.call())[-1]
> > f(a,b,c)
> [1] "a" "b" "c"
> > g = function(x,...) f(...)
> > g(x,a,b,c)
> [1] "..1" "..2" "..3"

Yes, that will (and must) happen. If you really want to go that route,
you need something in the veins of

> f <- function() match.call(sys.function(-1), call=sys.call(-1))
> g = function(x,...) f()
> g(x,a,b,c)
g(x = x, a, b, c)

> 
> > -----Original Message-----
> > From: Prof Brian Ripley [mailto:ripley at stats.ox.ac.uk] 
> > Sent: 02 March 2006 17:18
> > To: Matthew Dowle
> > Cc: 'r-help at stat.math.ethz.ch'
> > Subject: Re: [R] Deparsing '...'
> > 
> > 
> > f <- function(...) as.character(match.call())[-1]
> > > f(x,a,b,c*d)
> > [1] "x"     "a"     "b"     "c * d"
> > 
> > On Thu, 2 Mar 2006, Matthew Dowle wrote:
> > 
> > >
> > > Hi,
> > >
> > > The following function works, but is there a neater way to write it?
> > >
> > > f = function(x,...)
> > > {
> > >    # return a character vector of the arguments passed in after 'x'
> > >    gsub(" 
> > > ","",unlist(strsplit(deparse(substitute(list(...))),"[(,)]")))[-1]
> > > }
> > >
> > >> f(x,a,b,c*d)
> > > [1] "a"   "b"   "c*d"
> > >>
> > >
> > > Thanks.
> > 
> > -- 
> > Brian D. Ripley,                  ripley at stats.ox.ac.uk
> > Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> > University of Oxford,             Tel:  +44 1865 272861 (self)
> > 1 South Parks Road,                     +44 1865 272866 (PA)
> > Oxford OX1 3TG, UK                Fax:  +44 1865 272595
> >
> 
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-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907