I think this does it for you:
> a <-c("A","C","B","A","B","C")
>
> b <-c(10,20,30,40,50,60)
>
> C <-data.frame(a,b) # don't use 'c' as it is a primitive function - canbe
confusing
>
> N=10 #Number of Loops
>
>
>
> output.matix <- replicate(N, function(x){
+ .samp <- C[sample(nrow(C), replace=TRUE), ]
+ tapply(.samp$b, .samp$a, sum)
+ })
> # transpose if you want samples in columns
> output.matrix <- t(output.matrix)
> output.matrix
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
A 10 130 100 40 50 40 30 50 50 50
B 130 60 50 110 100 160 110 130 60 150
C 40 NA 60 80 120 60 NA 60 80 20
>
On 6/17/07, Economics Guy <[EMAIL PROTECTED]> 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]]
>
> ______________________________________________
> [email protected] 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.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem you are trying to solve?
[[alternative HTML version deleted]]
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
