[R] better loop for simulation

[Duncan Murdoch]

On 18/06/2016 6:12 PM, Naresh Gurbuxani wrote:
> I want to calculate a function many times over.  My solution below works, but does not seem very elegant.
>
> # my function to run many times over
> stud.score <- function(n.questions, mult.choice = 2) {
> 	prob.success <- 1 / mult.choice
> 	answers <- (runif(n.questions) < prob.success)
> 	return(sum(answers))
> }
>
> # my method to run above function 1000 times and store results
> count.df <- data.frame(n.count = rep(10, 1000))
> scores.df <- apply(count.df, 1, function(x) return(stud.score(x)))	
>
> Creating a data frame just to repeat the the count seems wasteful.  How can I generate scores.df without count.df?
>
> Thanks,

You don't need a data frame or a loop at all.  You're simulating 
binomial values, and R has rbinom() to do that in a vectorized way.

Duncan