Add a segment only to one facet using ggplot2

Question

As an example, I have this data frame, called my_data:

         Groups    FactorA    FactorB    FactorC N    value         sd        se                  


        

Answer 1

Put the data for the segment in data frame and also add columns FactorB and FactorC with levels for which you need to draw the segment.

data.segm<-data.frame(x=0.8,y=100,xend=1.2,yend=100,
                      FactorB="Condition1",FactorC="Condition1")

Now use this data frame to add segment. Also add inherit.aes=FALSE inside geom_segment() to ignore fill=FactorA set in ggplot().

  + geom_segment(data=data.segm,
               aes(x=x,y=y,yend=yend,xend=xend),inherit.aes=FALSE)+