How to use the variable names as titles in ggplot

Question

The default ggplot axis titles are the variable names:

library(ggplot2)
ggplot(mtcars, aes(cyl, wt)) +
  geom_point()

^{Created on 2021-09-10 by the reprex package (v0.3.0)}

I want to change my plot so that the x-axis title is instead the subtitle. I.e., something like + labs(x = NULL, subtitle = "cyl"). Is there a generalized way to do this?

Answer 1

I am not sure what your reason is to put it as a subtitle. Perhaps it is more worthwhile to simply move the position of the x-axis label?

ggplot(mtcars, aes(cyl, wt)) +
  geom_point() + 
  scale_x_discrete(position = "top") 

Answer 2

You may try -

library(ggplot2)

plot_data <- function(data, xvar, yvar) {
  name <- deparse(substitute(xvar))
  ggplot(data, aes({{xvar}}, {{yvar}})) +
    geom_point() + 
    labs(x = NULL, subtitle = name)
}

plot_data(mtcars, cyl, wt)