Random seed

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] 0.7561099 0.8544975 0.7070987 0.5274851 0.4269771
with_preserve_seed(runif(5))
#> [1] 0.7561099 0.8544975 0.7070987 0.5274851 0.4269771

# 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$integer.max, 1L), runif(5))
#> [1] 0.4458329 0.7415593 0.6138094 0.8396217 0.4743131
with_seed(seed, runif(5))
#> [1] 0.4458329 0.7415593 0.6138094 0.8396217 0.4743131
with_seed(seed <- sample.int(.Machine$integer.max, 1L), runif(5))
#> [1] 0.71317290 0.02839187 0.71035578 0.25841644 0.40783404