how to manipulate ... in the argument list

Hi,

I am looking for a documentation describing how to manipulate the
"..." . Searching R-intro.html gives to many not relevant hits for
"..."

What I want to do is something like this :


image.2 <- function(x, col , ...){
 # function is manipulating colors (adding a few)
 # since it changes colors it needs to update breaks if defined.

  breaks <- list(...)$breaks

 if( !is.null( list(...)$breaks ) ){
    #manipulate breaks

   image(x, col, breaks = breaks ,...)

  }else{
     image(x,col ,...)
  }
}

but in order to get it working I will need to remove breaks from ...
since otherwise I am getting multiple defined argument for breaks.

So how to manipulate the "..." argument? Or should I use a different pattern

best



--
Witold Eryk Wolski

Hi,

I am looking for a documentation describing how to manipulate the
"..." . Searching R-intro.html gives to many not relevant hits for
"..."

What I want to do is something like this :


image.2 <- function(x, col , ...){
  # function is manipulating colors (adding a few)
  # since it changes colors it needs to update breaks if defined.

   breaks <- list(...)$breaks

  if( !is.null( list(...)$breaks ) ){
     #manipulate breaks

    image(x, col, breaks = breaks ,...)

   }else{
      image(x,col ,...)
   }
}

but in order to get it working I will need to remove breaks from ...
since otherwise I am getting multiple defined argument for breaks.

So how to manipulate the "..." argument? Or should I use a different pattern

Hi,

I am looking for a documentation describing how to manipulate the
"..." . Searching R-intro.html gives to many not relevant hits for
"..."

What I want to do is something like this :


image.2 <- function(x, col , ...){
  # function is manipulating colors (adding a few)
  # since it changes colors it needs to update breaks if defined.

   breaks <- list(...)$breaks

  if( !is.null( list(...)$breaks ) ){
     #manipulate breaks

    image(x, col, breaks = breaks ,...)

   }else{
      image(x,col ,...)
   }
}

but in order to get it working I will need to remove breaks from ...
since otherwise I am getting multiple defined argument for breaks.

So how to manipulate the "..." argument? Or should I use a different pattern

best

Hi Witold,
use do.call()

list.args<-list(...)

#modify 'list.args' (add/delete/modify)

do.call(image, list.args)

best,
vito


Il 11/05/2016 10.45, Witold E Wolski ha scritto:

Hi,

I am looking for a documentation describing how to manipulate the
"..." . Searching R-intro.html gives to many not relevant hits for
"..."

What I want to do is something like this :


image.2 <- function(x, col , ...){
  # function is manipulating colors (adding a few)
  # since it changes colors it needs to update breaks if defined.

   breaks <- list(...)$breaks

  if( !is.null( list(...)$breaks ) ){
     #manipulate breaks

    image(x, col, breaks = breaks ,...)

   }else{
      image(x,col ,...)
   }
}

but in order to get it working I will need to remove breaks from ...
since otherwise I am getting multiple defined argument for breaks.

So how to manipulate the "..." argument? Or should I use a different
pattern

best

--
==============================================
Vito M.R. Muggeo
Dip.to Sc Statist e Matem `Vianelli'
Universit? di Palermo
viale delle Scienze, edificio 13
90128 Palermo - ITALY
tel: 091 23895240
fax: 091 485726
http://dssm.unipa.it/vmuggeo
Associate Editor, Statistical Modelling
===============================================