That gives:

Error in output.matrix[, i] <- as.vector(output.vector) :
        number of items to replace is not a multiple of replacement length

But I think that is close.

Thanks,

EG

On 6/17/07, David Barron <mothsailor@googlemail.com> wrote:
>
> I'm not sure I've completely understood this, but would this do what you
> want:
>
>
> for (i in 1:N){
>
> aa <- sample(a, replace=TRUE)
>
> c <-data.frame(b,aa)
>
> output <- by(c, aa, function(x) sum(x$b))
>
> output.matrix[,i] <- as.vector(output)
> }
>
>
>
> On 17/06/07, Economics Guy <economics.guy@gmail.com> wrote:
> > Based on help files and searching the archives and help from the
> listserv I
> > have managed to build my monte carlo program.
> >
> > However I cannot get the proper syntax for running the loop and storing
> the
> > output of each loop (which is a vector) into a matrix.
> >
> > I took out some of the crazy code I was writing, but here is what I
> have:
> >
> > --------------------
> >
> > rm(list = ls(all = TRUE))
> > # removes everything
> >
> > a <-c("A","C","B","A","B","C")
> >
> > b <-c(10,20,30,40,50,60)
> >
> > c <-data.frame(a,b)
> >
> > N=10 #Number of Loops
> >
> > output.matrix <- matrix(0.0,3,N)
> >
> > #I need to START LOOP HERE
> >
> > a <- sample(a, replace=TRUE)
> >
> > c <-data.frame(b,a)
> >
> > output.vector <- by(c, a, function(x) sum(x$b))
> >
> > output.vector <- as.vector(output)
> >
> > output.vector <- data.frame(output)
> >
> > #END LOOP here
> >
> >
> > --------------------------
> >
> > What I would like to have at the end is the "output.matrix" contain as a
> > column the  "output.vector" from  each iteration. The actual data frame
> I
> > will be running has 60,000 observations and I am going to run 20000
> > iterations so speed is important too.
> >
> > Thanks so much
> >
> > EG
> >
> >         [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
>
>
> --
> =================================
> David Barron
> Said Business School
> University of Oxford
> Park End Street
> Oxford OX1 1HP
>

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