rggplot2violin-plot

Restrain scattered jitter points within a violin plot by ggplot2


A following is used to generate the violin plot in ggplot2 :

ggplot(violin,aes(x=variable,y=log(value+0.5),color=Group)) + 
  geom_violin(scale="width") + 
  geom_jitter(aes(group=Group), position=position_jitterdodge()) + 
  stat_summary(fun.y="mean",geom="crossbar", mapping=aes(ymin=..y.., ymax=..y..), 
     width=1, position=position_dodge(),show.legend = FALSE) + 
  theme(axis.text.x = element_text(angle = 45, margin=margin(0.5, unit="cm")))

A resulting plot looks like following;

enter image description here

As you can see, some points are jittered outside the boundary of violin shape and I need to those points to be inside of the violin. I've played different levels of jittering but have had any success. I'd appreciate any pointers to achieve this.


Solution

  • It is a little bit old question but I think there is a better solution.

    As @Richard Telford pointed out in a comment, geom_sina (ggforce library) is the best solution IMO.

    simulate data

    df <- data.frame(data=rnorm(1200), 
                     group=rep(c("A","A","A", "B","B","C"),
                               200)
                     )
    

    make plot

    ggplot(df, aes(y=data,x=group,color=group)) +
      geom_violin()+
      geom_sina()
    

    result

    enter image description here

    Hope this is helpful.