On 10/11/2007 2:17 PM, Dale Steele wrote:
> Running the function below, tested using the cardiff dataset from
> splancs generates the following error. What changes do I need to
> make to get the function to work? Thanks. --Dale
>
>> gen.rpoints(events, poly, 99)
>> rpoints
> Error: object "rpoints" not found
>
> # test spatial data
> library(splancs)
> data(cardiff)
> attach(cardiff)
> str(cardiff)
> events <- as.points(x,y)
>
> ### non-working function ####
>
> gen.rpoints <- function(events, poly, nsim){
> rpoints <- array(0, dim=c(nrow(events),2,nsim))
> for (i in 1:nsim) {
> rpoints[, ,i] <- csr(poly, nrow(events))
> }
> }
You generate rpoints within the scope of the function, but you don't
return it. Change your function to
gen.rpoints <- function(events, poly, nsim){
rpoints <- array(0, dim=c(nrow(events),2,nsim))
for (i in 1:nsim) {
rpoints[, ,i] <- csr(poly, nrow(events))
}
rpoints
}
and call it as
rpoints <- gen.rpoints(...)
(There are ways to create variables outside of the scope of the
function, but you shouldn't use them.)
Duncan Murdoch
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