ggplot2: boxplot with all points distributed evenly in a row

Question

I have a boxplot generated with the following code:

b.males <- c(6, 7, 8, 8, 8, 9, 10, 10, 11, 11, 12, 12, 12, 12, 13, 14, 15)
b.females <- c(14, 13, 12, 12, 11, 10, 10, 9, 9, 9, 9, 9, 8, 8, 8, 7, 7, 7, 7)
b.total<-c(b.males,b.females)

b.m<-data.frame(b.males)
b.f<-data.frame(b.females)
b.t<-data.frame(b.total)

myList<-list(b.m, b.f, b.t)
df<-melt(myList)

colnames(df) <- c("class","count")
plt<-ggplot(df, aes(x=class,y=count))+geom_boxplot() 
plt + geom_point(aes(x = as.numeric(class) + 0, colour=class))

What I'd like to do is, for any given y-axis point, show all individual points in a row. For example, for b.males, I'd like to see 3 dots at 8, with the middle dot exactly in the center and the other two dots right next to it on either side.

I attempted:

plt + geom_point(aes(x = as.numeric(class) + 0, colour=class)) +
      geom_jitter(position=position_jitter(width=.1, height=0))

But this did not keep the points close together. Additionally, in some cases it would put multiple points to the right or left of the middle of the box, not distributing them evenly as I'd like.

Answer 1

You can use geom_dotplot() to add points - with arguments binaxis="y" your values binned according to y values (counts) and argument stackdir="center" ensures that dots are centered. To change the size of points use argument dotsize=

ggplot(df,aes(class,count))+geom_boxplot()+
  geom_dotplot(aes(fill=class),binaxis="y",stackdir="center",dotsize=0.5)