[R] outer

[Jagat Sheth]

Hi Oliver,

>>> Olivier Martin <olivier.martin at inrialpes.fr> 03/15 11:11 AM >>>
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 ?

The arguments x,y in fun are not labelling the cell indices in the outer product. Here are a couple simple examples of what fun will do for you.

> x <- 1:3
> y <- 1:3
> outer(x,y,FUN="fun")
     [,1] [,2] [,3]
[1,]    0    0    0
[2,]    0    0    0
[3,]    0    0    0

(Since x=y above, fun(x,y)=0 always)

> x <- 1:3
> y <- 2:4
> outer(x,y,FUN="fun")
     [,1] [,2] [,3]
[1,]    3    4    5
[2,]    4    5    6
[3,]    5    6    7
> 


Thanks for your help.

Jagat

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