Deterministic pseudorandom number generation in R

Question

I need to generate a vector of "random" numbers, except that they need to be fully deterministic. The distribution from which the numbers come is not so important. What is a simple way to do this in R?

The reason for not using something like runif is that it returns a different sequence every time it is called.

The reason for not generating one sequence (with runif) and reusing it is that the calls are made on different machines. I could hardcode the sequence into a script, but the length of the sequence needed is unknown at design-time, so a pseudorandom sequence based on some hardcoded seed is preferable.

score 8 · Accepted Answer · answered Nov 19 '13 at 14:59

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Are you aware of the set.seed() command?

R> set.seed(42); runif(3)           
[1] 0.914806 0.937075 0.286140
R> set.seed(42); runif(3)            # same seed, same numbers
[1] 0.914806 0.937075 0.286140
R> set.seed(12345); runif(3)         # different seed, different numbers
[1] 0.720904 0.875773 0.760982
R>

answered Nov 19 '13 at 14:59

Dirk Eddelbuettel

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Yep, thanks, meant to do that was got distracted. Hate when works get in the way :) – Dirk Eddelbuettel Nov 19 '13 at 15:08

score 1 · Answer 2 · answered Nov 19 '13 at 15:06

1

There is also the SoDa package (and manual [PDF]) which allows you to wrap other operations and recover the starting and ending seed. It's just a wrapper around set.seed() but you can check for yourself (e.g. in unit tests) more easily.

answered Nov 19 '13 at 15:06

Adam Hyland

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Deterministic pseudorandom number generation in R

2 Answers2