ggplot2 - jitter and position dodge together

Question

I am trying to recreate a figure from a GGplot2 seminar http://dl.dropbox.com/u/42707925/ggplot2/ggplot2slides.pdf.

In this case, I am trying to generate Example 5, with jittered data points subject to a dodge. When I run the code, the points are centered around the correct line, but have no jitter.

Here is the code directly from the presentation.

set.seed(12345) hillest<-c(rep(1.1,100*4*3)+rnorm(100*4*3,sd=0.2),        rep(1.9,100*4*3)+rnorm(100*4*3,sd=0.2)) rep<-rep(1:100,4*3*2) process<-rep(rep(c("Process 1","Process 2","Process 3","Process 4"),each=100),3*2) memorypar<-rep(rep(c("0.1","0.2","0.3"),each=4*100),2) tailindex<-rep(c("1.1","1.9"),each=3*4*100) ex5<-data.frame(hillest=hillest,rep=rep,process=process,memorypar=memorypar, tailindex=tailindex) stat_sum_df <- function(fun, geom="crossbar", ...) {stat_summary(fun.data=fun, geom=geom, ...) }  dodge <- position_dodge(width=0.9)  p<- ggplot(ex5,aes(x=tailindex ,y=hillest,color=memorypar))  p<- p + facet_wrap(~process,nrow=2) + geom_jitter(position=dodge) +geom_boxplot(position=dodge)   p 

Answer 1

In ggplot2 version 1.0.0 there is new position named position_jitterdodge() that is made for such situation. This postion should be used inside the geom_point() and there should be fill= used inside the aes() to show by which variable to dodge your data. To control the width of dodging argument dodge.width= should be used.

ggplot(ex5, aes(x=tailindex, y=hillest, color=memorypar, fill=memorypar)) +       facet_wrap(~process, nrow=2) +       geom_point(position=position_jitterdodge(dodge.width=0.9)) +       geom_boxplot(fill="white", outlier.colour=NA, position=position_dodge(width=0.9))