Overlay geom_points(aes(shape)) on geom

I am just trying to plot a ggplot figure of overlaying a points plot on a boxplot. I got very strange result and hope someone can tell me why and how to fix it.

Then I add shape mapping. You can see that all points changed completely. What I want is a same plot like above with only the point's shapes changed. i.e, the location of points should not change. I don't know why after adding shape mapping, the points are improperly assigned to the box group.

set.seed(1)
ggplot(data, aes(x, y, fill = fill))  
  geom_boxplot()  
  geom_point(aes(shape = shape), position=position_jitterdodge())

CodePudding user response：

In this case we want the position jittering to be "aware" of the two fill values which are distinguished the the fill aesthetic. Since the shapes here don't have a fill aesthetic, the layer doesn't automatically separate the two fill values before applying the jitter. To make the layer "aware" of the fill values, we could use

geom_point(aes(shape = shape, group = fill), 
               position=position_jitterdodge())

where group = fill tells the layer to group the points based on that variable, which will then be reflected in the way the points are jittered.