Expression and new line in plot labels [duplicate]

Answer 1

A fast solution is to add some spaces before the word "first".

Since plotmath does not support newlines, you can use mtext to create your lines one by one like this:

plot(1,1)
exp <- 2
Lines <- list(bquote("first line"),bquote("second line x"^2))
mtext(do.call(expression, Lines),side=3,line=1:0)

Answer 2

You can introduce a line break inside an expression:

bquote(atop("first line",
            "second line" ~ x ^ 2))

(I’m using bquote rather than expression here – both work in this case.)

Execute demo(plotmath) for more information and look at the documentation for atop.

boxplot apparently has some trouble interpreting expressions in its title. A simple fix is to plot the title separately:

boxplot(data, main = '')
title(bquote(atop("first line", "second line" ~ x ^ 2)))