How to dodge points in ggplot2 in R

Question

df = data.frame(subj=c(1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10), block=factor(rep(c(1,2),10)), acc=c(0.75,0.83,0.58,0.75,0.58,0.83,0.92,0.83,0.83,0.67,0.75,0.5,0.67,0.83,0.92,0.58,0.75,0.5,0.67,0.67))
ggplot(df,aes(block,acc,group=subj)) + geom_point(position=position_dodge(width=0.3)) + ylim(0,1) + labs(x='Block',y='Accuracy')

How do I get points to dodge each other uniformly in the horizontal direction? (I grouped by subj in order to get it to dodge at all, which might not be the correct thing to do...)

Answer 1

I think this might be what you were looking for, although no doubt you have solved it by now. Hopefully it will help someone else with the same issue.

A simple way is to use geom_dotplot like this:

ggplot(df,aes(x=block,y=acc)) + 
geom_dotplot(binaxis = "y", stackdir = "center", binwidth = 0.03)  + ylim(0,1) + labs(x='Block',y='Accuracy')

This looks like this:

Note that x (block in this case) has to be a factor for this to work.