R help - Feb 2014 - avoiding "multiple actual arguments" in default function behavior

Suppose I'm creating a function that sets default ylab and xlab behaviors:

plotx = function(x, y, ...){
    plot(x,y, ylab="", xlab="",...)
}

The problem is, on occasion, I actually want to override the defaults
in my function. I would like to do the following:

plotx(1:100, 1:100, xlab="I Don't Work!")


But I get the "multiple actual arguments" error message (which makes
sense). Does anyone know how to set a default (like plotx does), but
allow it to change if the user specifies the same argument via ...?

I tried doing something like this:

plotx = function(x, y, ...){
    args = list(...)
    yl = ifelse(!is.null(args$ylab), args$ylab, "")
    xl = ifelse(!is.null(args$xlab), args$xlab, "")
    plot(x,y, ylab=yl, xlab=xl,...)
}

but got the same error. I then started thinking that maybe I can
remove the ylab and xlab arguments from ..., but I don't know how I'd
do that. Any ideas of how to remove it? Or, is there a better way of
doing this? Thanks!

> Suppose I'm creating a function that sets default ylab and xlab
behaviors:
> 
> plotx = function(x, y, ...){
>     plot(x,y, ylab="", xlab="",...)
> }
> 
> The problem is, on occasion, I actually want to override the defaults
> in my function.
Make xlab and ylab arguments to your function.
  plotx2 <- function(x, y, ..., xlab="", ylab="") {
    plot(x, y, xlab=xlab, ylab=ylab, ...)
  }
(I put them after the ... in the argument list so they must be fully
named in the call.)

Bill Dunlap
TIBCO Software
wdunlap tibco.com

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org] On Behalf
> Of Dustin Fife
> Sent: Wednesday, February 05, 2014 8:11 AM
> To: r-help
> Subject: [R] avoiding "multiple actual arguments" in default
function behavior
> 
> Suppose I'm creating a function that sets default ylab and xlab
behaviors:
> 
> plotx = function(x, y, ...){
>     plot(x,y, ylab="", xlab="",...)
> }
> 
> The problem is, on occasion, I actually want to override the defaults
> in my function. I would like to do the following:
> 
> plotx(1:100, 1:100, xlab="I Don't Work!")
> 
> 
> But I get the "multiple actual arguments" error message (which
makes
> sense). Does anyone know how to set a default (like plotx does), but
> allow it to change if the user specifies the same argument via ...?
> 
> I tried doing something like this:
> 
> plotx = function(x, y, ...){
>     args = list(...)
>     yl = ifelse(!is.null(args$ylab), args$ylab, "")
>     xl = ifelse(!is.null(args$xlab), args$xlab, "")
>     plot(x,y, ylab=yl, xlab=xl,...)
> }
> 
> but got the same error. I then started thinking that maybe I can
> remove the ylab and xlab arguments from ..., but I don't know how
I'd
> do that. Any ideas of how to remove it? Or, is there a better way of
> doing this? Thanks!
> 
> ______________________________________________
> 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.

Hi,
Try:

?plotx <- function(x,y, ...){
?labels <- list(xlab="x",ylab="y")
?args <- modifyList(labels,list(x=x,...))
?do.call("plot",args)
?} 

?plotx(1:100,1:100,xlab="I Don't Work!")
A.K.


On Wednesday, February 5, 2014 11:14 AM, Dustin Fife <fife.dustin at
gmail.com> wrote:
Suppose I'm creating a function that sets default ylab and xlab behaviors:

plotx = function(x, y, ...){
? ? plot(x,y, ylab="", xlab="",...)
}

The problem is, on occasion, I actually want to override the defaults
in my function. I would like to do the following:

plotx(1:100, 1:100, xlab="I Don't Work!")


But I get the "multiple actual arguments" error message (which makes
sense). Does anyone know how to set a default (like plotx does), but
allow it to change if the user specifies the same argument via ...?

I tried doing something like this:

plotx = function(x, y, ...){
? ? args = list(...)
? ? yl = ifelse(!is.null(args$ylab), args$ylab, "")
? ? xl = ifelse(!is.null(args$xlab), args$xlab, "")
? ? plot(x,y, ylab=yl, xlab=xl,...)
}

but got the same error. I then started thinking that maybe I can
remove the ylab and xlab arguments from ..., but I don't know how I'd
do that. Any ideas of how to remove it? Or, is there a better way of
doing this? Thanks!

______________________________________________
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.