Question

In my work, I frequently display scatterplots using text labels. That’s meant a plot() command, followed by text(). I used cex to adjust to font size to what I wanted it very quickly.

I created a text scatterplot very quickly using qplot. But I can’t adjust the size fast. Here’s a silly code example:

data(state)
qplot(Income, Population, 
  data=as.data.frame(state.x77), 
  geom=c("smooth", "text"), method="lm", 
  label=state.abb)

Whereas in the old days I’d do:

plot(xlim=range(Income), ylim=range(Population),
  data=state.x77, type="n")
text(Income, Population, state.abb, 
     data=state.x77, cex=.5)

If I wanted the text size halved from what I saw at the defaults (oh, and I’d have to do a linear regression manually and add abline() to get the regression line — nice to do it all in one via ggplot2).

I know I can add a size adjustment with size, but it’s not a relative size adjustment like I’m used to. Hadley tweeted me to say that size is measured in mm, which isn’t fully intuitive to me. Since I often adjust the size of the plot, either in R or in LaTeX, an absolute scale isn’t as useful to me.

I must be missing something really simple. What is it?

Answer 1

I think you are tyring to adjust the size of the text itself, not the x-axis, right?

Here’s an approach using the ggplot() command.

ggplot(data = as.data.frame(state.x77), aes(x = Income, y = Population)) +
    geom_smooth(method = "lm", se = FALSE) +
    geom_text(aes(label = state.abb), size = 2.5)