tests/withSeed.R

In R.utils: Various Programming Utilities

library("R.utils")


# Reset seed
if (exists(".Random.seed", envir=globalenv())) {
  rm(list=".Random.seed", envir=globalenv())
}

# Generate a random number
y0 <- runif(1)
print(y0)

# Generate a random number using the same seed over and over
yp <- NULL
for (ii in 1:10) {
  y <- withSeed({
    runif(1)
  }, seed=0x42)
  print(y)
  # Assert identical
  if (!is.null(yp)) stopifnot(identical(y, yp))
  yp <- y
}

# Generate a random number
y <- runif(1)
print(y)



# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Visibility
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
res <- withVisible({
  withSeed({ 1 }, seed=42L)
})
str(res)
stopifnot(all.equal(res$value, 1))
stopifnot(res$visible)

x <- 0
res <- withVisible({
  withSeed({ x <- 1 }, seed=42L)
})
str(res)
stopifnot(all.equal(res$value, 1))
stopifnot(!res$visible)
stopifnot(all.equal(x, 1))


# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# With RNG state reset
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
res <- withSeed(sample.int(100L, size=1L), seed=NULL)