This is a very quick post because I discovered something that I’m pretty sure I’ll need to remember.

I needed to use a percentage sign (%) in a quarto report that was being rendered into LaTeX. As you probably know, % is a LaTeX comment and so we need escape it. We would normally do this by using \%. This meant that I needed to do something like.

gsub("%", "\%", "Percentage (%)")

Error: '\%' is an unrecognized escape in character string (<text>:1:13)

Except that as you can see this doesn’t work. This is due to \ being a special character. We need to escape it too, with the general rule of for every \ you want to appear use four or \\\\.

gsub("%", "\\\\%", "Percentage (%)")

[1] "Percentage (\\%)"

This looks like it hasn’t worked, except that print() isn’t showing us quite what is going on because it adds the escape characters. We can see what is actually happening using cat().

cat(gsub("%", "\\\\%", "Percentage (%)"))

Percentage (\%)

An alternative is to add fixed = TRUE, which just matches the pattern as is. Note: The print() difficulty above, which I was originally using for testing, still holds.

cat(gsub("%", "\\%", "Percentage (%)", fixed = TRUE))

Percentage (\%)