[R] Trouble with a loop

Joshua Wiley jwiley.psych at gmail.com
Tue Mar 6 00:43:38 CET 2012

Hi Kerry,

Right now at each iteration, you just overwrite everything.  If you
want a matrix, you need to instantiate Score as a matrix and then
assign the results into each element of it.  That said, I do not think
you really need a loop.  rpois() is vectorized, so you can in one pass
generate a large vector of data and use that for your model.

We do not have things like T, but something like:

Score <- matrix(NA, nrow = n.simul, ncol = 12)

for (your loop) {
  Score[, i] <- your formula

each of your models then would be assigned into the ith column of the
Score matrix, giving you the final product you expect.



On Mon, Mar 5, 2012 at 11:15 AM, kerry1912 <kerry1912 at hotmail.com> wrote:
> I am trying to run this loop but it keeps coming up with the following error:
> 'Error: no function to return from, jumping to top level'
> n.simul <- 1000
> A <- {for(i in 1:12){{
> nT <- rpois(n.simul, T[i])
> nP <- rpois(n.simul, P[i])
> nD <- rpois(n.simul, D[i])
> nC <- rbinom(n.simul, nT, C[i])
> Score <- (5*nT + 2*nC + 3*nP + 3*nD)
> }
> return(Score)}}
> My aim is to calculate nT, nP, nD and nC (which predicts the number of
> tries, penalties, drop goals and conversions scored in matches, which are
> simulated 1000 times which give 1000 scores)  then to use these to calculate
> the Score using these and multiplying by a constant for teams 1 to 12.
> So i am expecting this to give me a 1000 x 12 matrix of simulated scores
> Please ask in any other information is required.
> Many Thanks
> --
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Joshua Wiley
Ph.D. Student, Health Psychology
Programmer Analyst II, Statistical Consulting Group
University of California, Los Angeles

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