Set the random seed, in a pipeline or alone

Attach a seed to one expression at the end of a pipeline, as in sample(x, 5) |> set_seed(123), or set it alone like Stata's set seed 123 with set_seed(123).

Usage

set_seed(x, seed)

Arguments

x

An expression evaluated after setting the seed. When seed is omitted, x is the seed itself, as in set_seed(123).

seed

An integer for reproducibility.

Value

The expression's result, preserving its visibility. Used alone, set_seed() returns NULL invisibly.

Details

Calls set.seed() before evaluating x once. The global random-number state is changed and is not restored, including when x fails. Subsequent random draws continue from the state left by x.

With only one argument, that argument is the seed and must be a single finite number. A pipeline that forgets the seed therefore errors, unless its result happens to be a single number, which is then used as the seed.

See also

Other utility functions: capture(), timer()

Examples

sample(1:10, 8) |>
  set_seed(123)
#> [1]  3 10  2  8  6  9  1  7

# Repeating the seed reproduces the result
sample(1:10, 8) |>
  set_seed(123)
#> [1]  3 10  2  8  6  9  1  7

# Alone, like Stata's set seed 123
set_seed(123)
sample(1:10, 8)
#> [1]  3 10  2  8  6  9  1  7