Files
shiny/R/utils.R
2012-11-20 17:42:34 -08:00

104 lines
3.4 KiB
R

#' Make a random number generator repeatable
#'
#' Given a function that generates random data, returns a wrapped version of
#' that function that always uses the same seed when called. The seed to use can
#' be passed in explicitly if desired; otherwise, a random number is used.
#'
#' @param rngfunc The function that is affected by the R session's seed.
#' @param seed The seed to set every time the resulting function is called.
#' @return A repeatable version of the function that was passed in.
#'
#' @note When called, the returned function attempts to preserve the R session's
#' current seed by snapshotting and restoring
#' \code{\link[base]{.Random.seed}}.
#'
#' @examples
#' rnormA <- repeatable(rnorm)
#' rnormB <- repeatable(rnorm)
#' rnormA(3) # [1] 1.8285879 -0.7468041 -0.4639111
#' rnormA(3) # [1] 1.8285879 -0.7468041 -0.4639111
#' rnormA(5) # [1] 1.8285879 -0.7468041 -0.4639111 -1.6510126 -1.4686924
#' rnormB(5) # [1] -0.7946034 0.2568374 -0.6567597 1.2451387 -0.8375699
#'
#' @export
repeatable <- function(rngfunc, seed = runif(1, 0, .Machine$integer.max)) {
force(seed)
function(...) {
# When we exit, restore the seed to its original state
if (exists('.Random.seed', where=globalenv())) {
currentSeed <- get('.Random.seed', pos=globalenv())
on.exit(assign('.Random.seed', currentSeed, pos=globalenv()))
}
else {
on.exit(rm('.Random.seed', pos=globalenv()))
}
set.seed(seed)
do.call(rngfunc, list(...))
}
}
`%OR%` <- function(x, y) {
ifelse(is.null(x) || is.na(x), y, x)
}
`%AND%` <- function(x, y) {
if (!is.null(x) && !is.na(x))
if (!is.null(y) && !is.na(y))
return(y)
return(NULL)
}
`%.%` <- function(x, y) {
paste(x, y, sep='')
}
knownContentTypes <- Map$new()
knownContentTypes$mset(
html='text/html; charset=UTF-8',
htm='text/html; charset=UTF-8',
js='text/javascript',
css='text/css',
png='image/png',
jpg='image/jpeg',
jpeg='image/jpeg',
gif='image/gif',
svg='image/svg+xml',
txt='text/plain',
pdf='application/pdf',
ps='application/postscript',
xml='application/xml',
m3u='audio/x-mpegurl',
m4a='audio/mp4a-latm',
m4b='audio/mp4a-latm',
m4p='audio/mp4a-latm',
mp3='audio/mpeg',
wav='audio/x-wav',
m4u='video/vnd.mpegurl',
m4v='video/x-m4v',
mp4='video/mp4',
mpeg='video/mpeg',
mpg='video/mpeg',
avi='video/x-msvideo',
mov='video/quicktime',
ogg='application/ogg',
swf='application/x-shockwave-flash',
doc='application/msword',
xls='application/vnd.ms-excel',
ppt='application/vnd.ms-powerpoint',
xlsx='application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
xltx='application/vnd.openxmlformats-officedocument.spreadsheetml.template',
potx='application/vnd.openxmlformats-officedocument.presentationml.template',
ppsx='application/vnd.openxmlformats-officedocument.presentationml.slideshow',
pptx='application/vnd.openxmlformats-officedocument.presentationml.presentation',
sldx='application/vnd.openxmlformats-officedocument.presentationml.slide',
docx='application/vnd.openxmlformats-officedocument.wordprocessingml.document',
dotx='application/vnd.openxmlformats-officedocument.wordprocessingml.template',
xlam='application/vnd.ms-excel.addin.macroEnabled.12',
xlsb='application/vnd.ms-excel.sheet.binary.macroEnabled.12')
getContentType <- function(ext, defaultType='application/octet-stream') {
knownContentTypes$get(tolower(ext)) %OR% defaultType
}