# [R] subset with variable number of subset arguments

Erik Iverson iverson at biostat.wisc.edu
Fri Oct 31 16:22:50 CET 2008

```I think

subset(set, InfCode %in% x)

does it, where 'x' is your vector of ids (e.g., c(1,3,9) in your example
at the bottom)

Brar Piening wrote:
> I've got a big data.frame from which I need to extract data based on a variable number of Id's (InfCode).
> Until now I've been using the following dull solution as I never needed to search for more than 5 codes.
>
> Now my needs have increased faster than my R skills did and I need to call my function with about 25 values for x.
>
> There has to be a *apply or even simpler solution which (after RTM) I'm not able to figure out.
>
> Can anybody direct me to a possible solution?
>
> Regards,
>
> Brar
>
>
> GetInfCodeSubset <- function(set, x){
> 	if(1 == length(x))
> 		return(subset(set, (set\$InfCode == x[1])))
> 	else if(2 == length(x))
> 		return(subset(set, (set\$InfCode == x[1]) | (set\$InfCode == x[2])))
> 	else if(3 == length(x))
> 		return(subset(set, (set\$InfCode == x[1]) | (set\$InfCode == x[2]) | (set\$InfCode == x[3])))
> 	else if(4 == length(x))
> 		return(subset(set, (set\$InfCode == x[1]) | (set\$InfCode == x[2]) | (set\$InfCode == x[3]) | (set\$InfCode == x[4])))
> 	else if(5 == length(x))
> 		return(subset(set, (set\$InfCode == x[1]) | (set\$InfCode == x[2]) | (set\$InfCode == x[3]) | (set\$InfCode == x[4]) | (set\$InfCode == x[5])))
> 	else if(6 == length(x))
> 		return(subset(set, (set\$InfCode == x[1]) | (set\$InfCode == x[2]) | (set\$InfCode == x[3]) | (set\$InfCode == x[4]) | (set\$InfCode == x[5]) | (set\$InfCode == x[6])))
> 	else stop("Too many elements in x")
> }
>
> set <- data.frame(PatId = c(1:100), InfCode = rep(c(1:20), 5))
>
> GetInfCodeSubset(set, c(1,3,9))
>
> --
>
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