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
a character vector of image paths
whether to use PDF images automatically when the output format is LaTeX, 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 qualities than raster images like PNG when the output is LaTeX/PDF
the DPI (dots per inch) value to be used to calculate the output
width (in inches) of the images from the actual width (in pixels) divided
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.
This function is supposed to be used in R code chunks or inline R code
expressions. You are recommended to use forward slashes (
/) as path
separators instead of backslashes in the image paths.
The automatic calculation of the output width requires the png
package (for PNG images) or the jpeg package (for JPEG images). The
width will not be calculated if the chunk option
already provided or
dpi = NA.
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