[R] how to use "..."
Berend Hasselman
bhh at xs4all.nl
Thu Jan 17 15:57:35 CET 2013
On 17-01-2013, at 15:36, Ivan Calandra <ivan.calandra at u-bourgogne.fr> wrote:
> Dear users,
>
> I'm trying to learn how to use the "...".
>
> I have written a function (simplified here) that uses doBy::summaryBy():
> # 'dat' is a data.frame from which the aggregation is computed
> # 'vec_cat' is a integer vector defining which columns of the data.frame should be use on the right side of the formula
> # 'stat_fun' is the function that will be run to aggregate
> stat.group <- function(dat, vec_cat, stat_fun){
> require(doBy)
> df <- summaryBy(as.formula(paste0(".~",paste0(names(dat)[vec_cat],collapse="+"))), data=dat, FUN=stat_fun)
> return(df)
> }
>
> Example, works fine:
> my_data <- structure(list(cat = structure(c(1L, 1L, 1L, 1L, 1L, 2L, 2L,
> 2L, 2L, 2L), .Label = c("A", "B"), class = "factor"), varnum = c(-0.754816565434373,
> -1.94101630973709, -0.102461836059522, -0.519952759645808, -1.73772800855664,
> -1.13939178585609, 0.522356715260142, -0.701428514907824, 1.45197576541159,
> 0.0844567413828095)), .Names = c("cat", "varnum"), row.names = c(NA,
> -10L), class = "data.frame")
> stat.group(dat=my_data, vec_cat=1, stat_fun=mean)
>
>
> Now summaryBy() has an "..." argument and I would like to use it.
> For example, I would like to be able to add the trim argument to my call like this:
> stat.group(dat=my_data, vec_cat=1, stat_fun=mean, trim=0.2)
>
>
> I know I can do it using this "..." but I have no idea how to do it. I've tried to search for it, but a search with "..." doesn't yield interesting results!
>
This seems to work:
stat.group <- function(dat, vec_cat, stat_fun,...){
require(doBy)
df <- summaryBy(as.formula(paste0(".~",paste0(names(dat)[vec_cat],collapse="+"))), data=dat, FUN=stat_fun,...)
return(df)
}
and
stat.group(dat=my_data, vec_cat=1, stat_fun=mean, trim=0.2)
as the example for sumfun in the help for summaryBy shows.
Berend
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