R help - Dec 2015 - Weird behaviour function args in ellipses

Dears,

I'm having a weird behaviours when setting arguments in functions.

fn <- function(x, st="mean", b=NULL, col.range="black",
...){
  dots <- list(...)
  cat("col.range =", col.range, "\n")
  cat("dots =\n")
  print(dots)
}

fn(1, b=2,col="red")

# Output
col.range = red
dots list()

Why 'col' arguments are not in ellipses, but setting col.range to
'red'?

If I change the position of ellipses

fn2 <- function(x, ..., st="mean", b=NULL,
col.range="black"){
  dots <- list(...)
  cat("col.range =", col.range, "\n")
  cat("dots =\n")
  print(dots)
}

fn2(1, b=2, col="red")

# Output
col.range = black
dots $col
[1] "red"

It works! I'm using R version 3.2.2.

Best regards!

Mario

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On 11/12/2015 12:40 PM, Mario Jos? Marques-Azevedo
wrote:
> Dears,
>
> I'm having a weird behaviours when setting arguments in functions.
>
> fn <- function(x, st="mean", b=NULL,
col.range="black", ...){
>    dots <- list(...)
>    cat("col.range =", col.range, "\n")
>    cat("dots =\n")
>    print(dots)
> }
>
> fn(1, b=2,col="red")
>
> # Output
> col.range = red
> dots > list()
>
> Why 'col' arguments are not in ellipses, but setting col.range to
'red'?
See the R Language Definition manual, section 4.3.2.  Partial matching 
is used on arguments that precede ... in the function definition, exact 
matching on arguments that follow it.

Duncan Murdoch
>
> If I change the position of ellipses
>
> fn2 <- function(x, ..., st="mean", b=NULL,
col.range="black"){
>    dots <- list(...)
>    cat("col.range =", col.range, "\n")
>    cat("dots =\n")
>    print(dots)
> }
>
> fn2(1, b=2, col="red")
>
> # Output
> col.range = black
> dots > $col
> [1] "red"
>
> It works! I'm using R version 3.2.2.
>
> Best regards!
>
> Mario
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.

> On Dec 11, 2015, at 9:40 AM, Mario Jos? Marques-Azevedo <mariojmaaz at
gmail.com> wrote:
> 
> Dears,
> 
> I'm having a weird behaviours when setting arguments in functions.
> 
> fn <- function(x, st="mean", b=NULL,
col.range="black", ...){
>  dots <- list(...)
>  cat("col.range =", col.range, "\n")
>  cat("dots =\n")
>  print(dots)
> }
> 
> fn(1, b=2,col="red")
> 
> # Output
> col.range = red
Argument matching is done with `pmatch`. So "col" is a partial match
to "col.range".

See ?match.arg

> dots > list()
> 
> Why 'col' arguments are not in ellipses, but setting col.range to
'red'?
> 
> If I change the position of ellipses
> 
> fn2 <- function(x, ..., st="mean", b=NULL,
col.range="black"){
>  dots <- list(...)
>  cat("col.range =", col.range, "\n")
>  cat("dots =\n")
>  print(dots)
> }
> 
> fn2(1, b=2, col="red")
> 
> # Output
> col.range = black
> dots > $col
> [1] "red"
> 
> It works! I'm using R version 3.2.2.
It's been that way 'forever'.
> 
> Best regards!
> 
> Mario
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
David Winsemius
Alameda, CA, USA

Hi Duncan and David,

Thank you for explanation. I'm really disappointed with this R
"resource".
I think that partial match, mainly in function args, must be optional and
not default. We can have many problems and lost hours find errors (it occur
with me). I tried to find a solution to disable partial match, but it seems
that is not possible. Program with hacks for this will be sad.

Best regards!

Mario



On 11 December 2015 at 15:55, David Winsemius <dwinsemius at comcast.net>
wrote:
>
> > On Dec 11, 2015, at 9:40 AM, Mario Jos? Marques-Azevedo <
> mariojmaaz at gmail.com> wrote:
> >
> > Dears,
> >
> > I'm having a weird behaviours when setting arguments in functions.
> >
> > fn <- function(x, st="mean", b=NULL,
col.range="black", ...){
> >  dots <- list(...)
> >  cat("col.range =", col.range, "\n")
> >  cat("dots =\n")
> >  print(dots)
> > }
> >
> > fn(1, b=2,col="red")
> >
> > # Output
> > col.range = red
>
> Argument matching is done with `pmatch`. So "col" is a partial
match to
> "col.range".
>
> See ?match.arg
>
>
> > dots > > list()
> >
> > Why 'col' arguments are not in ellipses, but setting col.range
to 'red'?
> >
> > If I change the position of ellipses
> >
> > fn2 <- function(x, ..., st="mean", b=NULL,
col.range="black"){
> >  dots <- list(...)
> >  cat("col.range =", col.range, "\n")
> >  cat("dots =\n")
> >  print(dots)
> > }
> >
> > fn2(1, b=2, col="red")
> >
> > # Output
> > col.range = black
> > dots > > $col
> > [1] "red"
> >
> > It works! I'm using R version 3.2.2.
>
> It's been that way 'forever'.
>
> >
> > Best regards!
> >
> > Mario
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > 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.
>
> David Winsemius
> Alameda, CA, USA
>
>
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