[R] How to generate a matrix of Beta or Binomial distribution

[JeffND]

Hi folks,

I have a question about how to efficiently produce random numbers from Beta
and Binomial distributions. 

For Beta distribution, suppose we have two shape vectors shape1 and shape2.
I hope to generate a 10000 x 2 matrix X whose i th rwo is a sample from
reta(2,shape1[i]mshape2[i]). Of course this can be done via loops:

for(i in 1:10000)
{
X[i,]=rbeta(2,shape1[i],shape2[i])
}

However, the above code is time consuming. It would be better to directly
generate X without any loops. I tried the following code

X<- rbeta(2,shape1,shape2)

but it looks not right. So I was wondering if there is an R code doing this.

For Binomial distribution, I have a similar question.  I hope to generate a
10000 x n matrix Y whose i th row is a sample from rbinom(n,2,p[i]), where p
is a vector of binomial probabilities. We can also do it by loops

for(i in 1:10000)
{
Y[i,]=rbinom(n,2,p[i])
}

But it would be nice to do it without using any loops. Is this possible in
R?

Many thanks for great help and suggestions!
Jeff









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