R programming Generating random frequencies

Question

I'm trying to generate frequencies randomly to understand gene frequencies in a population using R. I tried this:

freq<- function(x,y)  #random frequency generator
    {rn<-sample(1:y,x)
    sum <- sum(rn)
    for(i in 1:x){
    RG[i]=rn[i]/sum}
    return(RG)
    }

Does anyone know how to constrain the sum to a particular value (say, 100) before division?

Answer 1

Follow this, it might help you:

1. Produce sample from uniform distribution
2. Sort the values
3. Insert 0 and 1
4. Use thresholds as cut-off points for values

Refer this example:

x <- sort(runif(10))
x
## [1] 0.06178627 0.20168193 0.26550866 0.37212390 0.57285336 0.62911404 0.66079779 0.89838968 0.90820779 0.94467527
x <- c(0,x,1)
y <- diff(x)
y
## [1] 0.061786270 0.139895661 0.063826732 0.106615236 0.200729464 0.056260681 0.031683749 0.237591892 0.009818105 0.036467479 0.055324731
sum(y)
## [1] 1