Back Compatibility Option for doRNG

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).

Description

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

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!

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)

Error in summary.connection(connection): invalid connectionres2 <- foreach(i=1:3) %dorng% runif(1)

Error in summary.connection(connection): invalid connectionstopifnot( !identical(attr(res, 'rng')[2:3], attr(res2, 'rng')[1:2]) )

Error in identical(attr(res, "rng")[2:3], attr(res2, "rng")[1:2]): object 'res' not foundres3 <- foreach(i=1:3, .options.RNG=123) %dorng% runif(1)

Error in summary.connection(connection): invalid connectionstopifnot( identical(res, res3) )

Error in identical(res, res3): object 'res' not found
# buggy behaviour in version < 1.4
doRNGversion("1.3")
res <- foreach(i=1:3) %dorng% runif(1)

Error in summary.connection(connection): invalid connectionres2 <- foreach(i=1:3) %dorng% runif(1)

Error in summary.connection(connection): invalid connectionstopifnot( identical(attr(res, 'rng')[2:3], attr(res2, 'rng')[1:2]) )

Error in identical(attr(res, "rng")[2:3], attr(res2, "rng")[1:2]): object 'res' not foundres3 <- foreach(i=1:3, .options.RNG=123) %dorng% runif(1)

Error in summary.connection(connection): invalid connectionstopifnot( !identical(res, res3) )

Error in identical(res, res3): object 'res' not found
# restore default RNG
RNGkind("default")
# restore to current doRNG version
doRNGversion(NULL)