ggplot two lines of title

Question

gg <- ggplot(data = data, aes(Type1Error_v, power_v, color = factor(test))) + 
  geom_line(alpha = 0.8) +
  geom_abline(intercept = 0, slope = 1) +
  labs(title = expression(paste(H[0], ": BN with ", mu[1], "=10, ", mu[2], "=11, ", sigma[1]^2, "=1, ", sigma[2]^2, "=50.23, ", rho, "=0.8, ", "N=50, p=10%, t~Exp(0.1)")), 
       x = "False Positive Rate (Type I Error Rate)", 
       y = "True Positive Rate (Power)") + 
  xlim(0, 1)

Is there a way to make the title in two lines? atop and \n both doesn't work here.

Is this not a duplicate of [ggplot2 two-line label with expression](https://stackoverflow.com/questions/13223846/ggplot2-two-line-label-with-expression)? Various solutions are proposed in that post. — Maurits Evers, Mar 06 '20 at 02:25
*What* doesn't work? Please be specific. There are quite a few different approaches. — Maurits Evers, Mar 06 '20 at 02:56
Because there are mu[1], sigma[1], etc. at different places, I cannot use atop or \n. — user53154, Mar 06 '20 at 03:02
There are other options given in that post. Not all use `"\n"` or `atop`. — Maurits Evers, Mar 06 '20 at 03:03

Maurits Evers · Answer 1 · 2020-03-06T03:06:25.933

An alternative to expression is to use ggtext (which requires ggplot >= 3.3.0); with ggtext you can format your title using HTML tags.

Here is an example:

library(ggtext)
ggplot(mtcars, aes(mpg, wt)) +
    geom_point() +
    ggtitle("H<sub>0</sub>: BN with &mu;<sub>1</sub>=10, &mu;<sub>2</sub>=11; &sigma;<sub>1</sub><sup>2</sup>=1, &sigma;<sub>2</sub><sup>2</sup>=50.23<br>Another line with more text") +
    theme(plot.title = element_markdown())

Here <sub> defines subscript, <sup> is for superscript, <br> introduces a line-break, and so on.

ggplot two lines of title

1 Answers1