You want to make a scatter plot.

Use geom_point(), and map one variable to x and one to y.

In the heightweight data set, there are a number of columns, but we’ll only use two in this example (Figure 5-1):

library(gcookbook) # For the data set

# List the two columns we'll use
heightweight[, c("ageYear", "heightIn")]

 ageYear heightIn
   11.92     56.3
   12.92     62.3
   12.75     63.3
...
   13.92     62.0
   12.58     59.3

ggplot(heightweight, aes(x=ageYear, y=heightIn)) + geom_point()

Figure 5-1. A basic scatter plot

To use different shapes in a scatter plot, set shape. A common alternative to the default solid circles (shape #16) is hollow ones (#21), as seen in Figure 5-2 (left):