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33 lines
1.2 KiB
R
33 lines
1.2 KiB
R
#' Make a random number generator repeatable
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#'
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#' Given a function that generates random data, returns a wrapped version of
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#' that function that always uses the same seed when called. The seed to use can
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#' be passed in explicitly if desired; otherwise, a random number is used.
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#'
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#' @param rngfunc The function that is affected by the R session's seed.
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#' @param seed The seed to set every time the resulting function is called.
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#' @return A repeatable version of the function that was passed in.
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#'
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#' @note When called, the returned function attempts to preserve the R session's
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#' current seed by snapshotting and restoring
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#' \code{\link[base]{.Random.seed}}.
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#'
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#' @examples
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#' rnormA <- repeatable(rnorm)
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#' rnormB <- repeatable(rnorm)
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#' rnormA(3) # [1] 1.8285879 -0.7468041 -0.4639111
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#' rnormA(3) # [1] 1.8285879 -0.7468041 -0.4639111
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#' rnormA(5) # [1] 1.8285879 -0.7468041 -0.4639111 -1.6510126 -1.4686924
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#' rnormB(5) # [1] -0.7946034 0.2568374 -0.6567597 1.2451387 -0.8375699
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#'
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#' @export
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repeatable <- function(rngfunc, seed = runif(1, 0, .Machine$integer.max)) {
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function(...) {
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currentSeed <- .Random.seed
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on.exit(.Random.seed <- currentSeed)
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set.seed(seed)
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do.call(rngfunc, list(...))
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}
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} |