Annotating text on individual facets in ggplot2 #2

Question

I'm also having some trouble with annotating text to individual facets in ggplot2 (w/ reference to related post: Annotating text on individual facet in ggplot2).

Data frame:

str(cfit_2)
'data.frame':   186 obs. of  5 variables:
 $ Participant: Factor w/ 31 levels "2","3","4","5",..: 1 2 3 4 5 6 7 8 9 10 ...
 $ Condition  : Factor w/ 2 levels "Active control group",..: 1 2 2 2 1 1 2 2 1 1 ...
 $ Time       : Factor w/ 2 levels "Pretest","Posttest": 1 1 1 1 1 1 1 1 1 1 ...
 $ CFIT       : num  10 13 17 11 19 15 19 11 15 16 ...
 $ Version    : Factor w/ 3 levels "Total CFIT","CFIT version 1",..: 1 1 1 1 1 1 1 1 1 1 ...

Code:

p<-ggplot(cfit_2,aes(Time,CFIT,fill=Condition))+
  scale_y_continuous(breaks=1:20)+
  scale_fill_manual(values=c("white","lightgrey"))+
  geom_violin()+
  theme_classic()+
  coord_cartesian(ylim=c(1, 20),xlim=c(1, 2))+
  theme(axis.line=element_blank())+
  facet_grid(.~Version)+ylab("CFIT raw score")+

  geom_segment(x=.3925,xend=.3925,y=1,yend=20)+
  geom_segment(x=1,xend=2,y=.015,yend=.015)+

 stat_summary(fun.y=mean,geom="point",position=position_dodge(w=.9))+
 stat_summary(fun.data=mean_cl_boot,geom="errorbar",position=position_dodge(w=.9),width=0)+

   geom_segment(data=data.segm_1,aes(x=x,xend=xend,y=y,yend=yend),inherit.aes=FALSE)+
   geom_segment(data=data.segm_2,aes(x=x,xend=xend,y=y,yend=yend),inherit.aes=FALSE)+
   geom_segment(data=data.segm_3,aes(x=x,xend=xend,y=y,yend=yend),inherit.aes=FALSE)+
   geom_segment(data=data.segm_1_2,aes(x=x,xend=xend,y=y,yend=yend),inherit.aes=FALSE)+
   geom_segment(data=data.segm_2_2,aes(x=x,xend=xend,y=y,yend=yend),inherit.aes=FALSE)+
   geom_segment(data=data.segm_3_2,aes(x=x,xend=xend,y=y,yend=yend),inherit.aes=FALSE)

Violin plot

What I want to do is to add "NS" or "*" next to every segment. Using the following data frame:

ann_text<-data.frame(Time=c("Pretest","Posttest","Pretest","Posttest","Pretest","Posttest"),CFIT=c(8,7,3,2,2,3),
       lab=c("NS","*","NS","*","NS","*"),
       Version=factor(c("Total CFIT","Total CFIT","CFIT version 1","CFIT version 1","CFIT version 2","CFIT version 2"),
                levels=c("Total CFIT","CFIT version 1","CFIT version 2")))

ann_text:

Time CFIT lab        Version
1  Pretest    8  NS     Total CFIT
2 Posttest    7   *     Total CFIT
3  Pretest    3  NS CFIT version 1
4 Posttest    2   * CFIT version 1
5  Pretest    2  NS CFIT version 2
6 Posttest    3   * CFIT version 2

... I get the following result from p+geom_text(data=ann_text,aes(label=lab)):

**Error in eval(expr, envir, enclos) : object 'Condition' not found**

---

Moving aes(fill=Condition) to geom_violin() gives the following plot:

Violin plot #2

Answer 1

The easiest way is to tell geom_text to not use Condition for the fill, by setting it to NULL. This way, you can keep fill in the ggplot call and have it applied to all other geoms, without the need to specify it each time.

Create data (since you didn't supply any)

cfit_2 <- data.frame(
  Time = c('Pretest', 'Posttest'),
  Condition = rep(c('Active control group', 'Training group'), each = 2),
  Version = rep(c('Total CFIT', 'CFIT version 1', 'CFIT version 2'), each = 40),
  CFIT = rnorm(120, 10, 3)
)

Use your plotting code

p<-ggplot(cfit_2,aes(Time,CFIT,fill=Condition))+
  #scale_y_continuous(breaks=1:20)+
  scale_fill_manual(values=c("white","lightgrey"))+
  geom_violin()+
  theme_classic()+
  #coord_cartesian(ylim=c(1, 20),xlim=c(1, 2))+
  theme(axis.line=element_blank())+
  facet_grid(.~Version)+ylab("CFIT raw score")+

  geom_segment(x=.3925,xend=.3925,y=1,yend=20)+
  geom_segment(x=1,xend=2,y=.015,yend=.015)+

  stat_summary(fun.y=mean,geom="point",position=position_dodge(w=.9))+
  stat_summary(fun.data=mean_cl_boot,geom="errorbar",position=position_dodge(w=.9),width=0)

(Note that I commented out two lines about the axes, since they were giving me troubles. I also removed the annotated lines, since you didn't supply data for those.)

Add the text

First create the coordinates where you want the asterisks and "NS"es.

ann_text<-read.table(text="
Time CFIT lab        Version
Pretest    15  NS     'Total CFIT'
Posttest    7   *     'Total CFIT'
Pretest    3  NS 'CFIT version 1'
Posttest    2   * 'CFIT version 1'
Pretest    2  NS 'CFIT version 2'
Posttest    3   * 'CFIT version 2'
",header=T)

Then annotate.

p + geom_text(data = ann_text, aes(label = lab, fill = NULL))

Result

Of course, the text doesn't look that nice (it's at the wrong y level), but that is because my data is different.