I use the following code:
library(foreach)
library(doParallel)
N<-5
cl<-makeCluster(8)
registerDoParallel(cl)
#loop
s8 <- foreach(i=1:N, .combine='rbind') %:%
foreach(j=1:N, .combine='c') %dopar% {
dis <-as.numeric (i+j) } ## In reality there something more complicated
stopCluster(cl)
I get the following result:
> s8
[,1] [,2] [,3] [,4] [,5]
result.1 2 3 4 5 6
result.2 3 4 5 6 7
result.3 4 5 6 7 8
result.4 5 6 7 8 9
result.5 6 7 8 9 10
I would like to get the upper diagonal matrix as followed:
> s8
[,1] [,2] [,3] [,4] [,5]
result.1 2 3 4 5 6
result.2 0 4 5 6 7
result.3 0 0 6 7 8
result.4 0 0 0 8 9
result.5 0 0 0 0 10
If I change the iterator of the inner loop to
foreach(j=i:N, .combine='c') %dopar% {
I don't get the required results.
Maybe this (although I would probably only parallelize the outer loop):
library(foreach)
library(doParallel)
N<-5
cl<-makeCluster(4)
registerDoParallel(cl)
#loop
#result is a list of vectors
s8 <- foreach(i=1:N) %:%
foreach(j=i:N, .combine='c') %dopar% {
as.numeric (i+j) } ## In reality there something more complicated
stopCluster(cl)
Post-processing to get same lengths:
s8 <- t(vapply(s8, function(x) {
x <- rev(x)
length(x) <- N
rev(x)
}, FUN.VALUE = numeric(N)))
s8[lower.tri(s8)] <- 0
# [,1] [,2] [,3] [,4] [,5]
#[1,] 2 3 4 5 6
#[2,] 0 4 5 6 7
#[3,] 0 0 6 7 8
#[4,] 0 0 0 8 9
#[5,] 0 0 0 0 10