devEval: Opens a new graphics device, evaluate (graphing) code, and closes device

Description

Opens a new graphics device, evaluate (graphing) code, and closes device.

Usage

devEval(type=getOption("device"), expr, initially=NULL, finally=NULL,
  envir=parent.frame(), name=NULL, tags=NULL, sep=getDevOption(type, "sep",
  default = ","), ..., ext=NULL, filename=NULL, path=getDevOption(type, "path",
  default = "figures"), field=getDevOption(type, name = "field"),
  onIncomplete=c("remove", "rename", "keep"), force=getDevOption(type, "force",
  default = TRUE), which=dev.cur(), .exprAsIs=FALSE, .allowUnknownArgs=FALSE)

Value

Returns a DevEvalFileProduct if the device generated an image file, otherwise an DevEvalProduct. If argument field is given, then the field of the

DevEvalProduct is returned instead.

Note that the default return value may be changed in future releases.

Arguments

type: Specifies the type of graphics device to be used. The device is created and opened using devNew(). Multiple types may be specified.
expr: The expression of graphing commands to be evaluated.
initially, finally: Optional expression:s to be evaluated before and after expr. If type specifies multiple devices, these optional expression:s are only evaluated ones.
envir: The environment where expr should be evaluated.
name, tags, sep: The fullname name of the image is specified as the name with optional sep-separated tags appended.
ext: The filename extension of the image file generated, if any. By default, it is inferred from argument type.
...: Additional arguments passed to devNew().
filename: The filename of the image saved, if any. By default, it is composed of arguments name, tags, sep, and ext. See also below.
path: The directory where then image should be saved, if any.
field: An optional character string specifying a specific field of the named result list to be returned.
onIncomplete: A character string specifying what to do with an image file that was incompletely generated due to an interrupt or an error.
force: If TRUE, and the image file already exists, then it is overwritten, otherwise not.
which: A vector of devices to be copied. Only applied if argument expr is missing.
.exprAsIs, .allowUnknownArgs: (Internal use only).

Generated image file

If created, the generated image file is saved in the directory specified by argument path with a filename consisting of the name followed by optional comma-separated tags and a filename extension given by argument ext.

By default, the image file is only created if the expr is evaluated completely. If it is, for instance, interrupted by the user or due to an error, then any incomplete/blank image file that was created will be removed. This behavior can be turned of using argument onIncomplete.

Author

Henrik Bengtsson

Examples

Run this code

# Plot to PNG using one whatever PNG device driver is available
res <- devEval("{png}", name="MyPlot", tags=c("10", "rnd"), aspectRatio=0.7, {
  plot(1:10)
})
print(res$pathname)
# [1] "figures/MyPlot,10,rnd.png"

str(res$dataURI)
# chr "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAeAA..."

## Plot to PDF using grDevices::pdf()
res <- devEval("pdf", name="MyPlot", tags=c("10", "rnd"), aspectRatio=0.7, {
  plot(1:10)
})
print(res$pathname)
# [1] "figures/MyPlot,10,rnd.pdf"


## Plot to EPS using R.devices::eps()
res <- devEval("eps", name="MyPlot", tags=c("10", "rnd"), aspectRatio=0.7, {
  plot(1:10)
})
print(res$pathname)
# [1] "figures/MyPlot,10,rnd.eps"

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