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]]
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]] > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.-- Yvan Richard DRAGONFLY Science Physical address: Level 5, 158 Victoria St, Te Aro, Wellington Postal address: PO Box 27535, Wellington 6141 New Zealand Ph: 04.385.9285 web page
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 generatedvalue> 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, inorder 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