[R] Loop Issue

[Yvan Richard]

Hi Ricardo
Assuming you have a good reason to use such approach (what are you
trying to do ultimately?), you can just increment your counter when
you get a good value, i.e.:

x <- numeric()
n <- 0
while (n < 10) {
    u <- log(runif(1, -1, 2))
    if (is.finite(u)) {
        n <- n+1
        x[n] <- u
    }
}
x

On 23 May 2014 12:11, Ricardo Rocha <ricardorocha23 at hotmail.com> 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?
>
> Thanks a lot,
>
> Ricardo
>         [[alternative HTML version deleted]]
>
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-- 
Yvan Richard

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