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Diffstat (limited to 'R')
| -rw-r--r-- | R/SyncRNG.R | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/R/SyncRNG.R b/R/SyncRNG.R new file mode 100644 index 0000000..84088b0 --- /dev/null +++ b/R/SyncRNG.R @@ -0,0 +1,69 @@ +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) + } + ) + ) |
