[R] outer

[Achim Zeileis]

Olivier Martin wrote:
> 
> Dear r-plus users,
> 
> i would like to use outer in the following case  outer(x,y,FUN="fun")
> i suppose that my function fun is of the following form:
> fun<-function(x,y)
> {
> if(y>x) return(x+y)
> if(y<=x) return(0)
> }
> My problem is that the command outer(x,y,FUN="fun") return me a
> null matrix instead of an upper triangular matrix.
> Is somebody have a solution ?

If you supply vectors to if(y>x), then just the first element is
actually used. ifelse does the job:

fun <- function(x,y) { ifelse(y>x, x+y, 0) }

should solve your problem
Achim

---------------------------
Institut für Statistik
Technische Universität Wien

> Thanks for your help.
> 
> 
> 
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