Make a random number generator repeatable

Given a function that generates random data, returns a wrapped version of that function that always uses the same seed when called. The seed to use can be passed in explicitly if desired; otherwise, a random number is used.

repeatable(rngfunc, seed = stats::runif(1, 0, .Machine$integer.max))

Arguments

rngfunc

The function that is affected by the R session's seed.

seed

The seed to set every time the resulting function is called.

Value

A repeatable version of the function that was passed in.

Note

When called, the returned function attempts to preserve the R session's current seed by snapshotting and restoring base::.Random.seed().

Examples

rnormA <- repeatable(rnorm)
rnormB <- repeatable(rnorm)
rnormA(3)  # [1]  1.8285879 -0.7468041 -0.4639111
#> [1] 1.0000840 0.7345643 1.7086582
rnormA(3)  # [1]  1.8285879 -0.7468041 -0.4639111
#> [1] 1.0000840 0.7345643 1.7086582
rnormA(5)  # [1]  1.8285879 -0.7468041 -0.4639111 -1.6510126 -1.4686924
#> [1]  1.0000840  0.7345643  1.7086582 -0.4016216  1.2537031
rnormB(5)  # [1] -0.7946034  0.2568374 -0.6567597  1.2451387 -0.8375699
#> [1] -0.1180581  0.3763196  0.2919217 -0.2744056 -0.5607413