knitr (version 1.40)

include_graphics: Embed external images in knitr documents

Description

When plots are not generated from R code, there is no way for knitr to capture plots automatically. In this case, you may generate the images manually and pass their file paths to this function to include them in the output. The major advantage of using this function is that it is portable in the sense that it works for all document formats that knitr supports, so you do not need to think if you have to use, for example, LaTeX or Markdown syntax, to embed an external image. Chunk options related to graphics output that work for normal R plots also work for these images, such as out.width and out.height.

Usage

include_graphics(
  path,
  auto_pdf = getOption("knitr.graphics.auto_pdf", FALSE),
  dpi = NULL,
  rel_path = getOption("knitr.graphics.rel_path", TRUE),
  error = getOption("knitr.graphics.error", TRUE)
)

Value

The same as the input character vector path but it is marked with special internal S3 classes so that knitr will convert the file paths to proper output code according to the output format.

Arguments

path

A character vector of image paths. Both local file paths and web paths are supported. Note that the auto_pdf and dpi arguments are not supported for web paths.

auto_pdf

Whether to use PDF images automatically when the output format is LaTeX. If TRUE, then e.g. foo/bar.png will be replaced by foo/bar.pdf if the latter exists. This can be useful since normally PDF images are of higher quality than raster images like PNG, when the output is LaTeX/PDF.

dpi

DPI (dots per inch) value. Used to calculate the output width (in inches) of the images. This will be their actual width in pixels, divided by dpi. If not provided, the chunk option dpi is used; if NA, the output width will not be calculated.

rel_path

Whether to automatically convert absolute paths to relative paths. If you know for sure that absolute paths work, you may set this argument or the global option knitr.graphics.rel_path to FALSE.

error

Whether to signal an error if any files specified in the path argument do not exist and are not web resources.