Making all arguments available for wrapped function in R

Question

How can I build flexibility into a wrapper function so that it can handle particular arguments being absent or present.

More specifically, I am building a wrapper for the gowdis function in the FD package and I want to give the user the option of including or excluding the arguments 'asym.bin' and 'ord'. Any advice given the example below:

library(FD)
?gowdis

x<-data.frame("Trait1" =c(1,1,0),
        "Trait2"=c(1,1,1),
        "Trait3" =c(1,1,0),
        "Trait4" =c(0,0,1))
        rownames(x)<-c("A","B","C")                 

w<-c(0.25,0.25,0.25,0.25)

m<-2    

asym.bin<-c(1,4)

wrapper.function = function(x,w,m) {
    gdis<-gowdis(x,w)
    gdis2<-gdis*m
    gdis2
}

#excluding the ord and asym.bin works fine
wrapper.function(x,w,m)
    A   B
B 0.5    
C 1.0 1.5

#but I want to give the user the option of including these wrapped arguments i.e.

wrapper.function = function(x,w,m,asym.bin,ord) {
    gdis<-gowdis(x,w,asym.bin,ord)
    gdis2<-gdis*m
    gdis2
}
wrapper.function(x,w,m)

However, this returns an error message

'Error in match.arg(ord) : argument "ord" is missing, with no default'

Answer 1

You can provide default values for arguments:

wrapper.function = function(x, w, m, asym.bin=NULL, ord='podani') {
    gdis <- gowdis(x, w, asym.bin, ord)
    gdis2 <- gdis * m
    gdis2
}

Alternative way of solving your problem could be (like @Jilber proposed in the comments) using ellipsis.

wrapper.function = function(x, w, m, ...) {
    gdis <- gowdis(x, w, m, ...)
    gdis2 <- gdis * m
    gids2
}