On Sep 1, 2012, at 19:20 , Petr Savicky wrote:
> On Sat, Sep 01, 2012 at 02:29:40AM -0700, Andras Farkas wrote:
>> Dear All,
>> ?
>> is there a way to set low and high limits to a simulation with rlnorm()?
>> ?
>> as an example:
>> ?a <-rlnorm(500,0.7,1)
>> ?
>> ?
>> I get the summary of
>> ?
>> Min. 1st Qu. Median Mean 3rd Qu. Max.
> 0.1175 1.0590 2.1270 3.4870 4.0260 45.3800
>>
>> I would like to set limits so that the simulated values minimum would be
>> greater then 0.5 and maximum of less than 30. If during simulation a
>> value?outside of the limits would be simulated, then I would like R to
>> "throw that value out" and go back to generate another random number instead
>> that would fit the limits criteria.
>
> Hi.
>
> If you want to generate one number at a time, try this
>
> while (1) {
> a <- rlnorm(1, 0.7, 1)
> if (0.5 < a && a < 30) break
> }
>
> If you want to generate a vector and avoid a loop over its components,
> try something like the following
>
> n <- 500
> while (1) {
> a <- rlnorm(2*n, 0.7, 1)
> a <- a[0.5 < a & a < 30] # only one & here
> if (length(a) >= n) break
> }
> a <- a[1:n]
>
> Hope this helps.
It's easier to use the inverse distribution function method:
n <- 500
u <- plnorm(30, .7, 1)
l <- plnorm(.5, .7, 1)
a <- qlnorm(runif(n, l, u), .7, 1)
summary(a)
hist(log(a))
--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd....@cbs.dk Priv: pda...@gmail.com
______________________________________________
R-help@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.
