doRNG (version 1.8.2)

doRNGversion: Back Compatibility Option for doRNG

Description

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

Usage

doRNGversion(x)

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).

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.

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

 registerDoSEQ() 

## 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)