Scatter diagram not displaying correctly

Question

Below is code I'm using to display a scatter diagram :

xx = c('test1' , 'test2' , 'test3') 
yy = c(6 , 7 , 8) 
df <- data.frame(xx , yy)
ggplot(df, aes(x=xx, y=yy)) + geom_point(alpha = .01) + theme_bw()

Why are the values of the scatter diagram not being displayed ?

Here is the output :

Answer 1

The alpha parameter alters transparency. Increase alpha to see the points.