R/mclapply_fixed.R

In parallelMap: Unified Interface to Parallelization Back-Ends

if (getRversion() >= "3.1.1") {
  mcmapply_fixed = mcmapply
} else {
  mcmapply_fixed = function(FUN, ..., MoreArgs = NULL, SIMPLIFY = TRUE, USE.NAMES = TRUE,
    mc.preschedule = TRUE, mc.set.seed = TRUE, mc.silent = FALSE,
    mc.cores = getOption("mc.cores", 2L), mc.cleanup = TRUE) {

    FUN <- match.fun(FUN)
    dots <- list(...)
    if (!length(dots)) {
      return(list())
    }
    lens <- sapply(dots, length)
    n <- max(lens)
    if (n && min(lens) == 0L) {
      stop("Zero-length inputs cannot be mixed with those of non-zero length")
    }
    answer <- if (mc.cores == 1L) { # <- only touched this line!
      .mapply(FUN, dots, MoreArgs)
    } else {
      X <- if (!all(lens == n)) {
        lapply(dots, function(x) rep(x, length.out = n))
      } else {
        dots
      }
      do_one <- function(indices, ...) {
        dots <- lapply(X, function(x) x[indices])
        .mapply(FUN, dots, MoreArgs)
      }
      answer <- mclapply(seq_len(n), do_one, mc.preschedule = mc.preschedule,
        mc.set.seed = mc.set.seed, mc.silent = mc.silent,
        mc.cores = mc.cores, mc.cleanup = mc.cleanup)
      do.call(c, answer)
    }
    if (USE.NAMES && length(dots)) {
      if (is.null(names1 <- names(dots[[1L]])) && is.character(dots[[1L]])) {
        names(answer) <- dots[[1L]]
      } else if (!is.null(names1)) {
        names(answer) <- names1
      }
    }
    if (!identical(SIMPLIFY, FALSE) && length(answer)) {
      simplify2array(answer, higher = (SIMPLIFY == "array"))
    } else {
      answer
    }
  }
}