Hi,
You may also try:
fun1 <- function(n, repl, val1, val2) {
mat1 <- suppressWarnings(replicate(repl, log(runif(n, val1, val2))))
mat1[!is.na(mat1)][seq(n)]
}
#Jim's function
fun2 <- function(init, final, val1, val2) {
i <- init
while (i < final) {
u <- runif(1, val1, val2)
if (u >= 0) {
x[i] <- log(u)
i <- i + 1
}
}
x
}
set.seed(49)
x1 <- fun1(10,3,-1,2)
set.seed(49)
x2 <- fun2(1,11,-1,2)
identical(x1,x2)
#[1] TRUE
###Speed comparison
set.seed(58)
system.time(x1 <- fun1(1e5,100, -1,2))
# user system elapsed
# 1.392 0.105 1.500
set.seed(58)
system.time(x2 <- fun2(1,1e5+1,-1,2))
# user system elapsed
# 31.930 0.988 32.973
identical(x1,x2)
#[1] TRUE
A.K.
On Friday, May 23, 2014 4:19 AM, Jim Lemon <j...@bitwrit.com.au> wrote:
On Thu, 22 May 2014 09:11:43 PM Ricardo Rocha wrote:
> Hi everybody.
>
> Consider the following exampling code:
>
> x=numeric()
> for(i in 1:10){
> u=runif(1,-1,2)
> x[i]=log(u)
> }
> This code, in each interation, generates a random value in the (-1,2)
> interval and then calculates the log of the value. When the generated
value
> is less than 0 the log produces a NaN, which gives a warning.
>
> What I want is to make it start over when a warning is produced, in
order to
> repeat it until a positive value is generated and therefore the log is
> calculated. Logically, would be like: "if there's a warning here, go back
> at the beginning and start over", without changing the iteration.
>
> Could someone help me with some directions?
>
Hi Ricardo,
Perhaps what you want is something like this:
i<-1
while(I < 11) {
u<-runif(1,-1,2)
if(u >= 0) {
x[i]<-log(u)
i<-i+1
}
}
Jim
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
