generate seed objects for parallel workers

get_parallel_seeds.R

get_parallel_seeds <- function(workers) {
	# Get current rng info and save
	orig_state <- .Random.seed
	orig_kind <- RNGkind()[1]
	# Reset the stream to get new rng's
	on.exit({
		RNGkind(orig_kind)
		assign(".Random.seed", orig_state, globalenv())
	})

	# Set to type used for multiple streams
	RNGkind("L'Ecuyer-CMRG")

	# Capture the seed to make more seeds.
	runif(1)
	.seed <- .Random.seed

	res <- vector(mode = "list", length = workers)
	for (i in seq_along(res)) {
		res[[i]] <- parallel::nextRNGSubStream(.seed)
		.seed <- parallel::nextRNGStream(.seed)
	}

	res
}

before_kind <- RNGkind()
set.seed(1)
before_rnd <- runif(1)

set.seed(1)
tmp <- get_parallel_seeds(3)
after_rnd <- runif(1)
RNGkind()

all.equal(before_kind, RNGkind())
all.equal(before_rnd, after_rnd)

# assign(".Random.seed", tmp[[1]], envir = .GlobalEnv)
# runif(1)

# assign(".Random.seed", tmp[[1]], envir = .GlobalEnv)
# runif(1)