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

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