Re: [R] Use of ellipses ... in argument list of optim(), integrate(), etc.

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Thu, 13 Mar 2008 18:00:50 +0000 (GMT)

There is an entry in the NEWS file for 2.6.0:

                 CHANGES IN R VERSION 2.6.0 SIGNIFICANT USER-VISIBLE CHANGES

     o	integrate(), nlm(), nlminb(), optim(), optimize() and uniroot()
 	now have '...' much earlier in their argument list.  This
 	reduces the chances of unintentional partial matching but
 	means that the later arguments must be named in full.

and there was a spate of instances of 'unintentional partial matching' at the time.

I have have no idea what you mean by 'ellipses or .' -- this is literally '...', and ellipses (e.g. Unicode U+226) do not work. From http://en.wikipedia.org/wiki/Ellipsis

   Most programming languages other than Perl6 require the ellipsis to be    written as a series of periods; a single (Unicode) ellipsis character    cannot be used.

Please use R-devel for questions about the design and development of R (see the posting guide).

On Thu, 13 Mar 2008, Ravi Varadhan wrote:

> Hi,
>
>
>
> I have noticed that there is a change in the use of ellipses or . in R
> versions 2.6.1 and later. In versions 2.5.1 and earlier, the . were always
> at the end of the argument list, but in 2.6.1 they are placed after the main
> arguments and before method control arguments. This results in the user
> having to specify the exact (complete) names of the control arguments, i.e.
> partial matching is not allowed.
>
>
>
> An example with integrate() :
>
>
>
>> integrate(function(x) exp(-x^2), lower=-Inf, upper=L, subdiv=1000)
>
>
>
> Error in f(x, ...) : unused argument(s) (subdiv = 1000)
>
>
>
>> integrate(function(x) exp(-x^2), lower=-Inf, upper=L, subdivisions=1000)
>
>
>
> 1.633051 with absolute error < 1.6e-06
>
>
>
>
>
> Here is an example with optim():
>
>
>
>> res <- optim(50, fw, meth="BFGS", control=list(maxit=20000, temp=20,
> parscale=20))
>
>
>
> Error in fn(par, ...) : unused argument(s) (meth = "BFGS")
>
>
>
>
>
> FYI, I am using R version 2.6.1 on Windows XP.
>
>
>
> May I ask what the rationale behind this change is and also about the pros
> and cons of the two different ways of specifying (.)?
>
>
>
> Thank you very much.
>
>
>
> Best,
>
> Ravi.
>
>
>
> ----------------------------------------------------------------------------
> -------
>
> Ravi Varadhan, Ph.D.
>
> Assistant Professor, The Center on Aging and Health
>
> Division of Geriatric Medicine and Gerontology
>
> Johns Hopkins University
>
> Ph: (410) 502-2619
>
> Fax: (410) 614-9625
>
> Email: rvaradhan_at_jhmi.edu
>
> Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html
>
>
>
> ----------------------------------------------------------------------------
> --------
>
>
>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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>

-- 
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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Received on Thu 13 Mar 2008 - 18:16:49 GMT

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