[R] how to use "..."

[Ivan Calandra]

Dear Patrick,

This is indeed a nice post to address the three dot issues.
It is definitely much clearer to me now

Thanks!
Ivan

--
Ivan CALANDRA
Université de Bourgogne
UMR CNRS/uB 6282 Biogéosciences
6 Boulevard Gabriel
21000 Dijon, FRANCE
+33(0)3.80.39.63.06
ivan.calandra at u-bourgogne.fr
http://biogeosciences.u-bourgogne.fr/calandra

Le 30/01/13 17:15, Patrick Burns a écrit :
> There is now a blog post that attempts to
> answer the question in the subject line:
>
> http://www.burns-stat.com/the-three-dots-construct-in-r/
>
> Pat
>
> On 17/01/2013 14:36, Ivan Calandra 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!
>>
>>
>> Thank you in advance for your help!
>> Ivan
>>
>