Test Rcpp parallel with R versions

testRcppparallel.R

library('microbenchmark')
library('Rcpp')
library('RcppParallel')
library('foreach')
library('parallel')
library('doParallel')
library('iterators')

sourceCpp('testrcpp.cpp')

##~~~~~~~~~~~~~~~~~~~R parallel~~~~~~~~~~~~~~~~~
SqrtRforeach <- function(orig, n = 8) {

  registerDoParallel(cores = n)

  itx <- iter(orig)

  res <- foreach(i = itx, .combine = c) %dopar% {
    return(sqrt(i))
  }

  ## stop multiple cores
  stopImplicitCluster()

  return(res)
}

SqrtRParSapply <- function(orig, n = 8) {

    cl <- makeCluster(n)
    registerDoParallel(cl)

    res <- parSapply(cl,
                     orig,
                     sqrt)

    ## stop multiple cores
    stopImplicitCluster()

    return(res)
}

SqrtR <- function(orig) {

  res <- numeric(length(orig))

  for (i in orig) {
    res[i] <- sqrt(orig[i])
  }

  return(res)

}
##~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

##~~~~~~~~~~~~~~~~test~~~~~~~~~~~~~~~~~~~~~
tmp1 <- runif(1e+7)

all.equal(SqrtCpp(tmp1),
          sqrt(tmp1),
          SqrtCppPara(tmp1),
          SqrtCppArma(tmp1))

microbenchmark(
  SqrtCpp(tmp1),
  sqrt(tmp1),
  SqrtCppPara(tmp1),
  SqrtCppArma(tmp1))

all.equal(SqrtCpp(tmp1),
          sqrt(tmp1),
          SqrtR(tmp1),
          SqrtRforeach(tmp1),
          SqrtRParSapply(tmp1),
          SqrtCppPara(tmp1),
          SqrtCppArma(tmp1))

microbenchmark(
    SqrtCpp(tmp1),
    sqrt(tmp1),
    SqrtR(tmp1),
    SqrtRforeach(tmp1),
    SqrtRParSapply(tmp1),
    SqrtCppPara(tmp1),
    SqrtCppArma(tmp1))
##~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~