R: Make a random number generator repeatable

repeatable {shiny} | R Documentation

## Make a random number generator repeatable

### Description

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.

### Usage

    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 `.Random.seed`.

### Examples

    rnormA <- repeatable(rnorm)
    rnormB <- repeatable(rnorm)
    rnormA(3)  # [1]  1.8285879 -0.7468041 -0.4639111
    rnormA(3)  # [1]  1.8285879 -0.7468041 -0.4639111
    rnormA(5)  # [1]  1.8285879 -0.7468041 -0.4639111 -1.6510126 -1.4686924
    rnormB(5)  # [1] -0.7946034  0.2568374 -0.6567597  1.2451387 -0.8375699

[Package shiny version 1.2.0 Index]