#' Save a ggplot with sensible defaults
#'
#' ggsave is a convenient function for saving a plot. It defaults to
#' saving the last plot that you displayed, and for a default size uses
#' the size of the current graphics device. It also guesses the type of
#' graphics device from the extension. This means the only argument you
#' need to supply is the filename.
#'
#' \code{grobsave} currently recognises the extensions eps/ps, tex (pictex),
#' pdf, jpeg, tiff, png, bmp, svg and wmf (windows only).
#'
#' @param filename file name/filename of plot
#' @param plot plot to save. This needs to be specified, otherwise the function will fail.
#' @param device device to use, automatically extract from file name extension
#' @param path path to save plot to (if you just want to set path and not
#' filename)
#' @param scale scaling factor
#' @param width width (defaults to the width of current plotting window)
#' @param height height (defaults to the height of current plotting window)
#' @param units units for width and height when either one is explicitly specified (in, cm, or mm)
#' @param dpi dpi to use for raster graphics
#' @param limitsize when \code{TRUE} (the default), \code{ggsave} will not
#' save images larger than 50x50 inches, to prevent the common error of
#' specifying dimensions in pixels.
#' @param ... other arguments passed to graphics device
#' @export
#' @examples
#' \dontrun{
#' ratings <- qplot(rating, data=movies, geom="histogram")
#' qplot(length, data=movies, geom="histogram")
#' ggsave("length-hist.pdf")
#' ggsave("length-hist.png")
#' ggsave("ratings.pdf", ratings)
#' ggsave("ratings.pdf", ratings, width=4, height=4)
#' # make twice as big as on screen
#' ggsave("ratings.pdf", ratings, scale=2)
#' }
#'
grobsave <- function(filename = default_name(plot), plot = NULL,
device = default_device(filename), path = NULL, scale = 1,
width = par("din")[1], height = par("din")[2], units = c("in", "cm", "mm"),
dpi = 300, limitsize = TRUE, ...) {
# This is the orginal line that is in ggsave - but removed for this function.
#if (!inherits(plot, "ggplot")) stop("plot should be a ggplot2 plot")
if(is.null(plot)) stop("plot needs to be provided. plot = last_plot() will not work here as only\n the last grob will be saved.")
if(!inherits(plot, c("grob", "ggplot"))) stop("plot should be a ggplot2 plot or a grob object")
eps <- ps <- function(..., width, height)
grDevices::postscript(..., width=width, height=height, onefile=FALSE,
horizontal = FALSE, paper = "special")
tex <- function(..., width, height)
grDevices::pictex(..., width=width, height=height)
pdf <- function(..., version="1.4")
grDevices::pdf(..., version=version)
svg <- function(...)
grDevices::svg(...)
wmf <- function(..., width, height)
grDevices::win.metafile(..., width=width, height=height)
emf <- function(..., width, height)
grDevices::win.metafile(..., width=width, height=height)
png <- function(..., width, height)
grDevices::png(..., width=width, height=height, res = dpi, units = "in")
jpg <- jpeg <- function(..., width, height)
grDevices::jpeg(..., width=width, height=height, res = dpi, units = "in")
bmp <- function(..., width, height)
grDevices::bmp(..., width=width, height=height, res = dpi, units = "in")
tiff <- function(..., width, height)
grDevices::tiff(..., width=width, height=height, res = dpi, units = "in")
default_name <- function(plot) {
paste(digest.ggplot(plot), ".pdf", sep="")
}
default_device <- function(filename) {
pieces <- strsplit(filename, "\\.")[[1]]
ext <- tolower(pieces[length(pieces)])
match.fun(ext)
}
units <- match.arg(units)
convert_to_inches <- function(x, units) {
x <- switch(units,
`in` = x,
cm = x / 2.54,
mm = x / 2.54 /10
)
}
convert_from_inches <- function(x, units) {
x <- switch(units,
`in` = x,
cm = x * 2.54,
mm = x * 2.54 * 10
)
}
# dimensions need to be in inches for all graphic devices
# convert width and height into inches when they are specified
if (!missing(width)) {
width <- convert_to_inches(width, units)
}
if (!missing(height)) {
height <- convert_to_inches(height, units)
}
# if either width or height is not specified, display an information message
# units are those specified by the user
if (missing(width) || missing(height)) {
message("Saving ", prettyNum(convert_from_inches(width * scale, units), digits=3), " x ", prettyNum(convert_from_inches(height * scale, units), digits=3), " ", units, " image")
}
width <- width * scale
height <- height * scale
if (limitsize && (width >= 50 || height >= 50)) {
stop("Dimensions exceed 50 inches (height and width are specified in inches/cm/mm, not pixels).",
" If you are sure you want these dimensions, use 'limitsize=FALSE'.")
}
if (!is.null(path)) {
filename <- file.path(path, filename)
}
device(file=filename, width=width, height=height, ...)
on.exit(capture.output(dev.off()))
print(plot)
invisible()
}
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