pbmclapply: Tracking mclapply with progress bar

Description

pbmclapply is a wrapper around the mclapply function. It adds a progress bar to mclapply function.

This function works on *nix (Linux, Unix such as macOS) system only due to the lack of fork() functionality, which is essential for mcapply, on Windows.

Usage

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pbmclapply(X, FUN, ...,
           mc.style = 3, mc.cores =getOption("mc.cores", 2L),
           ignore.interactive = F)

Arguments

X

a vector (atomic or list) or an expressions vector. Other objects (including classed objects) will be coerced by 'as.list'.

FUN

the function to be applied to.

...

optional arguments to FUN.

mc.cores

see mclapply.

mc.style

style of the progress bar. See txtProgressBar.

ignore.interactive

whether the interactive() is ignored. If set to TRUE, the progress bar will be printed even in a non-interactive environment (e.g. called by Rscript).

Examples

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# A lazy sqrt function which doesn't care about efficiency
lazySqrt <- function(num) {
  # Sleep randomly between 0 to 0.5 second
  Sys.sleep(runif(0.5))
  return(sqrt(num))
}

# A lazy and chatty sqrt function.
# An example of passing arguments to pbmclapply.
lazyChattySqrt <- function(num, name) {
  # Sleep randomly between 0 to 0.5 second
  Sys.sleep(runif(0.5))
  return(sprintf("Hello %s, the sqrt of %f is %f.", toString(name), num, sqrt(num)))
}

# Get the sqrt of 1-3 in parallel
result <- pbmclapply(1:3, lazySqrt)
chattyResult <- pbmclapply(1:3, lazyChattySqrt, "Bob")

Questions? Problems? Suggestions? or email at ian@mutexlabs.com.

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