Categorical scatter plot with mean segments using ggplot2 in R

Question

I am trying to plot a simple scatter plot for 3 groups, overlaying a segment indicating the mean for each group and labelling the groups. I have managed to get a scatter plot with error bars, but I would only like a segment indicating where the mean is. I also cannot seem to be getting the group labelling right.

To get the summary statistics I am using the function "summarySE" from this page.

Is there any simpler way to do this, and to get a segment instead of a point for the mean?

I really appreciate your help!

library(ggplot2)
library(plyr)

df <- data.frame(tt = rep(1:3, each = 40),
       val = round(rnorm(120, m = rep(c(4, 5, 7), each = 40))))

# After loading the summarySE function:

dfc <- summarySE(df, measurevar="val", groupvars="tt")


ggplot(dfc, aes(tt, val), main="Scatter plot with mean bars", 
      xlab="Groups", ylab="Values", names=c("Group1", "Group2", "Group3"))+
  geom_jitter(aes(tt, val), data = df, colour = I("red"), 
               position = position_jitter(width = 0.05)) +
  geom_point(size = 3) +
  geom_errorbar(aes(ymin=val-sd, ymax=val+sd), width = 0.01, size = 1)

Answer 1

You can use geom_crossbar() and use val as y, ymin and ymax values. With scale_x_continuous() you can change x axis labels for original data or use @agstudy solution to change original data and labels will appear automatically.

ggplot()+
  geom_jitter(aes(tt, val), data = df, colour = I("red"), 
              position = position_jitter(width = 0.05)) +
  geom_crossbar(data=dfc,aes(x=tt,ymin=val, ymax=val,y=val,group=tt), width = 0.5)+
  scale_x_continuous(breaks=c(1,2,3),labels=c("Group1", "Group2", "Group3"))

Answer 2

To get the group labelling , You can change continuous tt a factor like this :

dfc$tt <- factor(dfc$tt,labels=c("Group1", "Group2", "Group3"))

Of course before calling summarySE and creating dfc.

and using crossbar as mentioned in the other solution below , you get: