[R] Simulation based on runif to get mean

[Rui Barradas]

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
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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.
>>
> 
> 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
>