ggplot2: multiple colours in stat_summary

Question

I have a plot in which I am displaying individual values from multiple subjects, coloured by group. Added to that are means per group, calculated using stat_summary.

Answer 1

You need to create different values for the mapping to color:

ggplot(data=iris, 
       aes(x=Sepal.Length, y=Sepal.Width, color=Species)) + 
  geom_line() + geom_point() + theme_bw() +
  stat_summary(fun.y=mean, geom="line", size=1.5,
               linetype="dotted", aes(color=paste("mean", Species)))

You can then use scale_color_manual to get specific colors.