doRNGversion: Back Compatibility Option for doRNG

In doRNG: Generic Reproducible Parallel Backend for 'foreach' Loops

Back Compatibility Option for doRNG

Description

Sets the behaviour of %dorng% foreach loops from a given version number.

Usage

doRNGversion(x)

Arguments

x	version number to switch to, or missing to get the currently active version number, or NULL to reset to the default behaviour, i.e. of the latest version.

Value

a character string If x is missing this function returns the version number from the current behaviour. If x is specified, the function returns the old value of the version number (invisible).

Behaviour changes in versions

1.4

The behaviour of doRNGseed, and therefore of %dorng% loops, changed in the case where the current RNG was L'Ecuyer-CMRG. Using set.seed before a non-seeded loop used not to be identical to seeding via .options.RNG. Another bug was that non-seeded loops would share most of their RNG seed!

1.7.4

Prior to this version, in the case where the RNG had not been called yet, the first seeded %dorng% loops would not give the identical results as subsequent loops despite using the same seed (see https://github.com/renozao/doRNG/issues/12).

This has been fixed in version 1.7.4, where the RNG is called once (sample(NA)), whenever the .Random.seed is not found in global environment.

Examples

## Seeding when current RNG is L'Ecuyer-CMRG
RNGkind("L'Ecuyer")

doRNGversion("1.4")
# in version >= 1.4 seeding behaviour changed to fix a bug
set.seed(123)
res <- foreach(i=1:3) %dorng% runif(1)
res2 <- foreach(i=1:3) %dorng% runif(1)
stopifnot( !identical(attr(res, 'rng')[2:3], attr(res2, 'rng')[1:2]) )
res3 <- foreach(i=1:3, .options.RNG=123) %dorng% runif(1)
stopifnot( identical(res, res3) )

# buggy behaviour in version < 1.4
doRNGversion("1.3")
res <- foreach(i=1:3) %dorng% runif(1)
res2 <- foreach(i=1:3) %dorng% runif(1)
stopifnot( identical(attr(res, 'rng')[2:3], attr(res2, 'rng')[1:2]) )
res3 <- foreach(i=1:3, .options.RNG=123) %dorng% runif(1)
stopifnot( !identical(res, res3) )

# restore default RNG  
RNGkind("default")
# restore to current doRNG version
doRNGversion(NULL)

doRNG documentation built on Jan. 16, 2023, 5:07 p.m.