[SOLVED] How do you add both data frame values and math operators to geom

How do you add both data frame values and math operators to geom_text in R?

I'm attempting to use geom_text to create a label 'Ankle Absorption W = -0.52 - 0.13 x Hop Height'. My understanding is that I need to use %*% within expression() to output the x sign. The numbers are stored in a data frame. I'm having difficulty getting expression() to read the data frame values - it simply prints the data frame name.

Here's my current code:

ggplot(mtcars, aes(hp, wt)) + 
    geom_text( label = expression( 'Ankle Absorption W = ' 
    mtcars$hp[1],' ', mtcars$hp[2] %*% 'Hop Height' ) )

The result for the mtcars$hp[1] portion was simply printing 'mtcars$hp[1]' rather than the stored values.

I've looked at other posts and tried using bquote() and paste() within expression() but it just prints 'bquote' and 'paste'.

Solution

Here's an example using ggtext with a standard data set (with shorter variable names):

ggplot(mtcars, aes(hp, wt)) +
  ggtext::geom_richtext(aes(label = glue::glue("{hp} &times; {wt}")), 
                        fill = NA, label.color = NA)