with_seed() runs code with a specific random seed and resets it afterwards.

with_preserve_seed() runs code with the current random seed and resets it afterwards.

with_seed(seed, code)

local_seed(seed, .local_envir = parent.frame())

with_preserve_seed(code)

local_preserve_seed(.local_envir = parent.frame())

Arguments

seed

[integer(1)]
The random seed to use to evaluate the code.

code

[any]
Code to execute in the temporary environment

.local_envir

[environment]
The environment to use for scoping.

Value

[any]
The results of the evaluation of the code argument.

See also

withr for examples

Examples

# Same random values: with_preserve_seed(runif(5))
#> [1] 0.10169262 0.76999328 0.08906143 0.53659237 0.26213892
with_preserve_seed(runif(5))
#> [1] 0.10169262 0.76999328 0.08906143 0.53659237 0.26213892
# Use a pseudorandom value as seed to advance the RNG and pick a different # value for the next call: with_seed(seed <- sample.int(.Machine$integer.max, 1L), runif(5))
#> [1] 0.5885083 0.3289879 0.4357050 0.2184870 0.3697503
with_seed(seed, runif(5))
#> [1] 0.5885083 0.3289879 0.4357050 0.2184870 0.3697503
with_seed(seed <- sample.int(.Machine$integer.max, 1L), runif(5))
#> [1] 0.6099326 0.6076366 0.4936592 0.6276273 0.5535448