RMarkdown - high quality (gg)plots in non-pdf output

This is a quick update to an earlier post about changing/improving the output of graphics, i.e. ggplot, in “other” RMarkdown output formats, e.g. MS Word.

In my view one of the annoying features of RMarkdown, knitr, and friends is that graphics/ggplots knitted to MS Word look … let’s say … shabby. I am cognisant of the technicalities, read a lot about it, but it is way above my head how to re-write what would be needed. Thus, I am using one of the workarounds: setting the print device to cairo and using a decent (higher) dpi value.

# the workaround
if (knitr::opts_knit$get("rmarkdown.pandoc.to") != "latex") {
  knitr::opts_chunk$set(dpi = 300, dev.args = list(type = "cairo"))

This works well wenn the Rmd is knitted or rendered programmatically. However, executing the code chunk by hand in RStudio will throw an error. Obviously, the if() conditions throws an error as the Rmd is not knitted/rendered - or in other words read in a knitr/pandoc pipeline.

For quite a while I circumnavigated that problem by either commenting out the lines above # if(knitr::opts ... or removing the r-engine pointer from the code chunk header, i.e. ```{ setup, ... } ... instead of ```{r setup, ...} ..... Obviously, the commenting out needs to be removed before knitting the document to its less-shabby-graphics format or you have to live with a code-block/monospace text block unless putting the r back in. Both options require to keep this in mind and/or fix it. Being categorically bad in remembering this or rolling the eyes when I yet saw the text block after rendering the Rmd, I regularly scanned for other ways of doing it.

The other day I tried to understand {purrr}’s safely() function. It did what I wanted it to do in the other context: accepting a function to throw an error without interrupting the script/further execution.
It took a while but then it sank in with me that this is the behaviour I was looking for to remove the workaround obstacles.

Hence, I wrap the configuration call into a function and call it with purrr::safely().

# helper function to ensure nice(r) looking graphics in MS Word output
# defines dpi and cairo, if not wrapped in safely, the chunk fails if run by
# hand, i.e. if(knitr::opts()$get has issues if run by hand!
knit_quality_vis <- function(){
  if (knitr::opts_knit$get("rmarkdown.pandoc.to") != "latex") {
    knitr::opts_chunk$set(dpi = 300, dev.args = list(type = "cairo"))
  }
} 
purrr::safely(.f = high_quality_vis)

Works like a charm when the code chunk is run by hand, run-all-chunks-above, or with a run-all call. And performs like expected when knitted/rendered programmatically.

If anyone out there has found a better way to do this, please give me a nudge!