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library(methods)
#' A Reference Class for SyncRNG
#'
#' @field seed The seed for the random number generator
#' @field state The current state of the RNG, should not be modified by the
#' user
#'
#' @examples
#' s <- SyncRNG(seed=123456)
#' for (i in 1:10)
#' cat(s$randi(), '\n')
#'
SyncRNG <- setRefClass('SyncRNG',
fields=list(
seed='numeric',
state='numeric'
),
methods=list(
initialize=function(..., seed=0) {
"Initialize the RNG using the C function R_syncrng_seed"
seed <<- seed
tmp <- .Call('R_syncrng_seed',
as.numeric(seed))
state <<- tmp[1:4]
callSuper(...)
},
randi=function() {
"Generate a single random 32-bit integer"
tmp <- .Call('R_syncrng_rand',
as.numeric(state))
state <<- tmp[1:4]
return(tmp[5])
},
rand=function() {
"Generate a single random float in the range [0, 1)"
r <- randi()
return (r * 2.3283064365387e-10)
},
randbelow=function(n) {
"Generate a random integer below a given number"
maxsize <- 2^32
if (n >= maxsize) {
warning(paste("Underlying random generator ",
"does not supply\n enough bits ",
"to choose from a population ",
"range this large.\n"))
return(round(rand() * n))
}
rem <- maxsize %% n
limit <- (maxsize - rem) / maxsize
r <- rand()
while (r >= limit)
r <- rand()
return(round(r*maxsize) %% n)
},
shuffle=function(x) {
"Randomly shuffle a provided array of values"
y <- x
for (i in rev(1:(length(y)-1))) {
j <- randbelow(i+1)
tmp <- y[i+1]
y[i+1] <- y[j+1]
y[j+1] <- tmp
}
return(y)
}
)
)
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