run a for loop in parallel in R
Thanks for your feedback. I did look up parallel after I posted this question.
Finally after a few tries, I got it running. I have added the code below in case it is useful to others
library(foreach)library(doParallel)#setup parallel backend to use many processorscores=detectCores()cl <- makeCluster(cores[1]-1) #not to overload your computerregisterDoParallel(cl)finalMatrix <- foreach(i=1:150000, .combine=cbind) %dopar% { tempMatrix = functionThatDoesSomething() #calling a function #do other things if you want tempMatrix #Equivalent to finalMatrix = cbind(finalMatrix, tempMatrix)}#stop clusterstopCluster(cl)Note - I must add a note that if the user allocates too many processes, then user may get this error: Error in serialize(data, node$con) : error writing to connection
Note - If .combine in the foreach statement is rbind , then the final object returned would have been created by appending output of each loop row-wise.
Hope this is useful for folks trying out parallel processing in R for the first time like me.
References:http://www.r-bloggers.com/parallel-r-loops-for-windows-and-linux/https://beckmw.wordpress.com/2014/01/21/a-brief-foray-into-parallel-processing-with-r/