Arguments matching
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
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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
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Web http://www.steph280.freesurf.fr/
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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/