save partial results in foreach loop in R

Question

I want to know how many loops have been done and save the results of each finished loop, but assign and cat function are not working.

library(doParallel)
library(foreach)
library(Matrix)

rm(list=ls())


cl=makeCluster(2)
registerDoParallel(cl)

  sink("report.txt")
result=foreach (n=1:10,.packages="Matrix" )%dopar%{
  variable <-sparseMatrix(dims = c(100,150), i={1}, j={1},x=0)


  cat(sprintf("tastk %d is complete \n",n),append=TRUE)
  assign(paste("variable",n,sep=""),variable)
  return(variable)

} 

sink()

Possible duplicate of [How can I \`print\` or \`cat\` when using parallel](https://stackoverflow.com/questions/16717461/how-can-i-print-or-cat-when-using-parallel) — F. Privé, Oct 02 '18 at 16:22
I have tried but, after implementing cl=makeCluster(20,outfile="report.txt") When I open the report during the loop, any line is written. — LauC, Oct 02 '18 at 17:04
not really, the variable is not created and it writes in the text file when it wants. I think is something related to the ram memory, but I don´t know how to manage it. — LauC, Oct 05 '18 at 13:46

score 1 · Answer 1 · answered Oct 03 '18 at 06:37

This works perfectly fine on my Linux computer:

library(doParallel)
library(foreach)
library(Matrix)

rm(list=ls())


cl=makeCluster(2, outfile = "report.txt")
registerDoParallel(cl)

result=foreach (n=1:10,.packages="Matrix" )%dopar%{

  variable <-sparseMatrix(dims = c(100,150), i={1}, j={1},x=0)      

  cat(sprintf("task %d is complete \n",n))
  assign(paste("variable",n,sep=""),variable)
  return(variable)

} 

stopCluster(cl)

save partial results in foreach loop in R

1 Answers1