Using different font styles in annotate (ggplot2)

Question

I'm using the code below to generate a simple chart with some annotations:

require(ggplot2); data(mtcars) ggplot(mtcars, aes(x = wt, y = mpg)) +    geom_point() +   annotate("text", x = 4, y = 25, label = "This should be bold\nand this not",            colour = "red") +   geom_vline(xintercept = 3.2, colour = "red") 

On that chart I would like to apply bold font to the first part of the phrase in the text annotation:

This should be bold

but the I wish for the remaining part of the text to remain unaltered with respect to the font face and style.

Answer 1

If you don't have a problem with splitting it up in two annotations, you could just do:

annotate("text", x = 4, y = 25, label = "This should be bold",        colour = "red", fontface =2)+ annotate("text", x = 4, y = 24, label = "and this not",        colour = "red") 

Answer 2

How about using plotmath syntax with parse = TRUE:

ggplot(mtcars, aes(x = wt, y = mpg)) +      geom_point() +     annotate("text", x = 4, y = 25,              label = 'atop(bold("This should be bold"),"this should not")',             colour = "red", parse = TRUE) +     geom_vline(xintercept = 3.2, colour = "red")