I find Unicode extremely useful in my ggplots for symbols and special characters in legends. For instance, much easier than using expressions, I use the unicode for a suffix, e.g.
labs(x = "g₁", y = "g₂").
Also I usually want to save the plots as PDF, not as some pixmap format – PDFs are much smaller while offering unlimited resolution.
There are actually two separate problems that surface here.
- Some Unicode characters, while visible in the program code, are replaced by block outlines in the plot on screen. That’s bad, but one could live with it.
- The standard
ggsaveto PDF replaces the unicode characters with ellipses (…). That’s unacceptable.
New Solution (2022-12-17, tested in MacOS Ventura)
To produce a PDF with intact Unicode:
Install the package
Cairo, and use
library(Cairo); ggsave(filename='whatever.pdf', device=cairo_pdf, family="Arial Unicode MS", …)
Other fonts are certainly possible, “Arial Unicode MS” contains all glyphs I need so far.
From here on continues the old blog entry:
Solutions (tested in MacOS, High Sierra & Catalina)
- To see the Unicode on the screen:
In your ggplot code, add this line somewhere
ad lib replacing Helvetica with any font on your machine that does contain the desired Unicode characters, e.g. “Arial Unicode MS”.
- To produce a PDF with intact Unicode:
Install the package
Cairo, and use ggsave like so
library(Cairo); ggsave(filename='whatever.pdf', device=cairo_pdf, …)
- To produce a PNG (or JPG) with intact Unicode:
Easy: the standard
ggsaverenders Unicode correctly for these targets.
I dug into this deeply because on one of my machines ggsave suddenly threw an error
failed to load cairo DLL.
Hmm… after lots of trying to understand & solve this (like re-installing Cairo with the wonderful RStudio, re-installing cairo in brew, …), I finally found on stack exchange this advice
brew cask install r
This re-installed R, and Cairo now also works! There still are signs and wonders :)!
What a nice task to spend time with in times of Corona…