Capture a plot as a saved file

Easily generates a .png file (or other graphics file) from a plotting expression.

capturePlot(
  expr,
  filename = tempfile(fileext = ".png"),
  device = defaultPngDevice(),
  width = 400,
  height = 400,
  res = 72,
  ...
)

Arguments

expr

A plotting expression that generates a plot (or yields an object that generates a plot when printed, like a ggplot2). We evaluate this expression after activating the graphics device (device).

filename

The output filename. By default, a temp file with .png extension will be used; you should provide a filename with a different extension if you provide a non-PNG graphics device function.

device

A graphics device function; by default, this will be either grDevices::png(), ragg::agg_png(), or Cairo::CairoPNG(), depending on your system and configuration. See defaultPngDevice().

width, height, res, ...

Additional arguments to the device function.

See also

plotTag() saves plots as a self-contained <img> tag.

Examples

# Default settings
res <- capturePlot(plot(cars))

# View result
if (interactive()) browseURL(res)

# Clean up
unlink(res)

# Custom width/height
pngpath <- tempfile(fileext = ".png")
capturePlot(plot(pressure), pngpath, width = 800, height = 375)
#> [1] "/tmp/RtmpwXEWaf/file2a6a7867584c.png"
if (interactive()) browseURL(pngpath)
unlink(pngpath)

# Use a custom graphics device (e.g., SVG)
if (capabilities("cairo")) {
  svgpath <- capturePlot(
    plot(pressure),
    tempfile(fileext = ".svg"),
    grDevices::svg,
    width = 8, height = 3.75
  )
  if (interactive()) browseURL(svgpath)
  unlink(svgpath)
}