Message-ID: <5.2.1.1.0.20041126165202.02266330@biomserv.univ-lyon1.fr>
Date: 2004-11-26T21:58:34Z
From: Stéphane Dray
Subject: Arguments matching
In-Reply-To: <5.2.1.1.0.20041126161941.022688c0@magellan.umontreal.ca>
I just precise my problem (and correct the subject).
Is there a way to obtain a list where each element has the name of the
argument (as interpreted by R). The problem with my approach is that if the
user do not type the name of the argument, this element of the list
(returned by as.list(as.call(appel1$callf))) has no name.
I suppose that a solution could be obtained using formals, match.args...
but I did not find it.
Thanks
At 16:30 26/11/2004, Stephane DRAY wrote:
>Hello list,
>I have a question concerning argument matching I have read R Language
>Definition before).
>I have a function multxby2 which takes as argument the call to another
>function f1.
>I would like to take the values of xx from the call to f1 and use it in
>multxby2.
>
>Here is an example:
>
>
>multxby2 <- function(callf) {
> appel1<-match.call()
> appel<-as.list(as.call(appel1$callf))
>
> px<-pmatch(names(appel),"xx")
>
> if(sum(is.na(px))!=length(appel)) print(appel[[which(!is.na(px))]]*2)
> # else ...
>
>}
>
>f1=function(xx=2,y=3){}
>
>multxby2(f1(x=3))
>
>My problem is due to the various ways that a user can enter its arguments,
>how to be sure to get xx from various call such as:
>
>multxby2(f1(3,2))
>multxby2(f1(y=2,3))
>
>Is there a way to do that avoiding a lot of "if" and how to solve the last
>case ? My practical case takes functions with around 20 arguments.
>
>Thanks in advance,
>
>Sincerely.
>St??phane DRAY
>--------------------------------------------------------------------------------------------------
>
>D??partement des Sciences Biologiques
>Universit?? de Montr??al, C.P. 6128, succursale centre-ville
>Montr??al, Qu??bec H3C 3J7, Canada
>
>Tel : (514) 343-6111 poste 1233 Fax : (514) 343-2293
>E-mail : stephane.dray at umontreal.ca
>--------------------------------------------------------------------------------------------------
>
>Web http://www.steph280.freesurf.fr/
>
>______________________________________________
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>PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
St??phane DRAY
--------------------------------------------------------------------------------------------------
D??partement des Sciences Biologiques
Universit?? de Montr??al, C.P. 6128, succursale centre-ville
Montr??al, Qu??bec H3C 3J7, Canada
Tel : (514) 343-6111 poste 1233 Fax : (514) 343-2293
E-mail : stephane.dray at umontreal.ca
--------------------------------------------------------------------------------------------------
Web http://www.steph280.freesurf.fr/