Annotate ggplot with superscripts and subscripts with commas

Question

I'm trying to annotate my ggplot with three lines. I've given up trying the atop() way because I have three lines and each line has a superscript or subscript and I keep running into errors.

I would like to alter the following annotations on this plot:

• the "149" should read "1,49" in subscript
• the "R2adj" should have the 2 superscript and the adj subscript.

mod1 <- lm(data = mtcars, mpg ~ cyl)
F_stat <- (car::Anova(mod1))$`F value`[1]

ggplot(mtcars, aes(x = wt, y = mpg)) +
  geom_point() +
  annotate(geom = 'text',
         x = 4,
         y = 30, 
         label = paste("F[149] ==", F_stat), 
         parse = TRUE,
         hjust = 0) +
  annotate(geom = 'text',
         x = 4,
         y = 25, 
         label = paste("p < 0.001"), 
         parse = TRUE,
         hjust = 0) +
  annotate(geom = 'text',
         x = 4,
         y = 20, 
         label = paste(
           "R^2",
           "[adj]",
           "==",
           round(summary(mod1)$adj.r.squared, 3)), 
         parse = TRUE,
         hjust = 0)

I've looked at several other stackoverflow posts and cannot figure it out. Any advice? Thank you!

Answer 1

To get the adj in subscript and the 2 in superscript, try R[adj]^2 instead of R^2[adj]. To get a comma in the subscripted number, wrap the number in quotes. You'll need a backslash escape for the quotes, so it's paste("F[\"1,49\"] ==", 122.952)

ggplot(mtcars, aes(x = wt, y = mpg)) +
  geom_point() +
  annotate(geom = 'text',
           x = 4,
           y = 30, 
           label = paste("F[\"1,49\"] ==", 122.952), 
           parse = TRUE,
           hjust = 0) +
  annotate(geom = 'text',
           x = 4,
           y = 25, 
           label = paste("p < 0.001"), 
           parse = TRUE,
           hjust = 0) +
  annotate(geom = 'text',
           x = 4,
           y = 20, 
           label = paste(
             "R[adj]^2",
             "==",
             0.709), 
           parse = TRUE,
           hjust = 0)