[R] How to append the random no.s for different variables in the same data.frame

[R. Michael Weylandt]

On Wed, Sep 12, 2012 at 7:51 AM, Vincy Pyne <vincy_pyne at yahoo.ca> wrote:
> Dear R helpers,
>
> (At the outset I sincerely apologize if I have not put forward my following query properly, though I have tried to do so.)
>
>
> Following is a curtailed part of my R - code where I am trying to generate say 100 random no.s for each of the products under consideration.
>
>
> library(plyr)
> n = 100
>
> my_code = function(product, output_avg, output_stdev)
>
>     {
>
> BUR_mc = rnorm(n, output_avg, output_stdev)
>
> sim_BUR = data.frame(product, BUR_mc)
>
> write.csv(data.frame(sim_BUR), 'sim_BUR.csv', row.names = FALSE)
>
> return(list(output_avg, output_stdev))
>
>     }
>
>
> result <- dlply(.data = My_data, .variables = "product", .fun = function(x)
>                  my_code(product = x$product, output_avg = x$output_avg,
>                  output_stdev = x$output_stdev))
>
>
> There are some 12 products (and this may vary each time). In my original code, the "return" statement returns me some other output. Here for simplicity sake, I am just using the values as given in input.
>
>
> PROBLEM - A :
>
> I want to store the random no.s (BUR_mc) as generated above for each of the products and store them in a single data.frame. Now when I access 'sim_BUR.csv', I get the csv file where the random nos. generated for the last product are getting stored. I need something like
>
> product          random no
> product1         .......
> product1         .......
> .............................
>
> product1         .......                      # (This is 100th value generated for product1)
> product2         .......
> product2         .......
>
> ............................
> ............................
> ............................
>
> Problem - B
>
> Also, is it possible to have more than one 'return' statements in a given function?

No: if you want to return multiple values, put them in a list and return that:

f <- function(n, nn){
   x <- rnorm(n)
   y <- rexp(nn)
   ret <- list(x = x, y = y)
   return(ret)
}

Cheers,
M

>
> Thanking in advance
>
> Vincy
>
>         [[alternative HTML version deleted]]
>
>
> ______________________________________________
> R-help at r-project.org 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.
>