[R] R parallel / foreach - aggregation of results

[jim holtman]

Try this chance to actually return values:


library(doParallel)
Simpar3 <- function(n1) {
   L2distance <- matrix(NA, ncol=n1, nrow=n1)
   data <- rnorm(n1)
   diag(L2distance)=0
   cl <- makeCluster(4)
   registerDoParallel(cl)
   x <- foreach(j=1:n1)  %dopar% {
     library(np)
     datj <- data[j]
     for(k in j:n1) {
       L2distance[j,k] <- k*datj
     }
     L2distance  # return the value
   }
   stopCluster(cl)
   return(x)
 }
 Res <- Simpar3(100)


Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.

On Fri, Jul 31, 2015 at 8:39 AM, Martin Spindler <Martin.Spindler at gmx.de>
wrote:

> Dear all,
>
> when I am running the code attached below, it seems that no results are
> returned, only the predefined NAs. What mistake do I make?
> Any comments and help is highly appreciated.
>
> Thanks and best,
>
> Martin
>
>
> Simpar3 <- function(n1) {
>   L2distance <- matrix(NA, ncol=n1, nrow=n1)
>   data <- rnorm(n1)
>   diag(L2distance)=0
>   cl <- makeCluster(4)
>   registerDoParallel(cl)
>   foreach(j=1:n1)  %dopar% {
>     library(np)
>     datj <- data[j]
>     for(k in j:n1) {
>       L2distance[j,k] <- k*datj
>     }
>   }
>   stopCluster(cl)
>   return(L2distance)
> }
>
> Res <- Simpar3(100)
>
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