R help - Jun 2007 - Storing output vector form a loop as a matrix

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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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 at 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 at 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

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 <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.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?

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