[R] Simulation based on runif to get mean

[Eric Berger]

Or a shorter version of Rui's approach:

set.seed(2511)    # Make the results reproducible
fun <- function(n){
  f <- function(){
    c(mean(runif(5,1,10)),mean(runif(5,10,20)))
  }
  replicate(n, f())
}
fun(10)

On Tue, Jan 30, 2018 at 12:03 PM, Rui Barradas <ruipbarradas at sapo.pt> wrote:

> Hello,
>
> Another way would be to use ?replicate and ?colMeans.
>
>
> set.seed(2511)    # Make the results reproducible
>
> fun <- function(n){
>     f <- function(){
>         a <- runif(5, 1, 10)
>         b <- runif(5, 10, 20)
>         colMeans(cbind(a, b))
>     }
>     replicate(n, f())
> }
>
> fun(10)
>
> Hope this helps,
>
> Rui Barradas
>
>
> On 1/30/2018 8:58 AM, Daniel Nordlund wrote:
>
>> On 1/29/2018 9:03 PM, smart hendsome via R-help wrote:
>>
>>> Hello everyone,
>>> I have a question regarding simulating based on runif.  Let say I have
>>> generated matrix A and B based on runif. Then I find mean for each matrix A
>>> and matrix B.  I want this process to be done let say 10 times. Anyone can
>>> help me.  Actually I want make the function that I can play around with the
>>> number of simulation process that I want. Thanks.
>>> Eg:
>>> a <- matrix(runif(5,1, 10))
>>>
>>> b <- matrix(runif(5,10, 20))
>>>
>>> c <- cbind(a,b); c
>>>
>>> mn <- apply(c,2,mean); mn
>>>
>>> Regards,
>>> Zuhri
>>>
>>>     [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide http://www.R-project.org/posti
>>> ng-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>> Here is a straight forward implementation of your code in a function with
>> a parameter for the number simulations you want to run.
>>
>> sim <- function(n){
>>    mn <- matrix(0,n, 2)
>>    for(i in 1:n) {
>>      a <- runif(5,1, 10)
>>      b <- runif(5,10, 20)
>>      c <- cbind(a,b)
>>      mn[i,] <- apply(c, 2, mean)
>>      }
>>    return(mn)
>>    }
>> # run 10 iterations
>> sim(10)
>>
>> In your case, there doesn't seem to be a need to create a and b as
>> matrices; vectors work just as well.  Also, several of the statements could
>> be combined into one.  Whether this meets your needs depends on what your
>> real world task actually is.
>>
>>
>> Hope this is helpful,
>>
>> Dan
>>
>>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posti
> ng-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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