[R] A coding question

[xpRt.wannabe]

Uwe and Ben,

Thank you both for your help.

To me, both sets of code seem to do the job and should produce the
same results.  However, as a test I inserted set.seed( ) as follows.
Unless I put set.seed( ) in the wrong lines, the results produced by
both sets of code turn out to be different.  I am baffled.

y <- replicate(10, {
        set.seed(123)
        rp <- rpois(8, 5)
        mysum <- sapply(rp, function(x) {
            set.seed(123)
            x <- rnorm(x)
            x <- x - max(0, x-15) + max(0, x-90)
            sum(x)
        })
     })

##

tmpf <- function() {
set.seed(123)
x <- rnorm(rpois(1,5))
sum(ifelse(x>90,x-75,pmin(x,15)))
}
replicate(10,replicate(8,tmpf()))

On 6/2/06, Uwe Ligges <ligges at statistik.uni-dortmund.de> wrote:
> xpRt.wannabe wrote:
>
> > Dear List:
> >
> > I have the follow code:
> >
> > y <- replicate(10,replicate(8,sum(rnorm(rpois(1,5)))))
> >
> > Now I need to apply the following condition to _every_ randomly generated
> > Normal number in the code above:
> >
> > x - max(0,x-15) + max(0,x-90), where x represents the individual Normal
> > numbers.
> >
> > In other words, the said condition needs to be applied before
> > replicate(...(replicate(...(sum(...))) takes place.
> >
> > Any help would be greatly appreciated.
>
>
> y <- replicate(10, {
>         rp <- rpois(8, 5)
>         mysum <- sapply(rp, function(x) {
>             x <- rnorm(x)
>             x <- x - max(0, x-15) + max(0, x-90)
>             sum(x)
>         })
>      })