Example of parallel vectorized functions using snow

Parallel Computing.R

require(snow)

VariabletoExport <- 5

TheFunction <- function(x){
  TimeWaster <- mean(rnorm(100000, 0, 1))
  x^2 + TimeWaster + VariabletoExport
  }

FunctionInput <- 1:1000

### Unparallelized ###

StartTime <- Sys.time()
  FunctionOutput <- lapply(FunctionInput, TheFunction)
ProcessTime <- Sys.time() - StartTime
ProcessTime

### Parallelized ###

StartTime <- Sys.time()
  TheCluster <- makeCluster(8, type = "SOCK")
  clusterSetupRNG(TheCluster, type = "RNGstream")
  clusterExport(TheCluster, c("VariabletoExport"))
    FunctionOutput <- parSapply(TheCluster, FunctionInput, TheFunction)
  stopCluster(TheCluster)
ProcessTime <- Sys.time() - StartTime
ProcessTime

See also: http://mockquant.blogspot.com/2011/02/simple-examplehow-to-use-foreach-and.html