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.
I would like the two means to be coloured by group, but in colours other than the individual data. This turns out to be difficult, at least when using stat_summary. I have the following code:
ggplot(data=dat,
aes(x=Round, y=DV, group=Subject, colour=T1)) +
geom_line() + geom_point() + theme_bw() +
stat_summary(fun.y=mean, geom="line", size=1.5,
linetype="dotted", color="black",
aes(group=T1))
Which produces this example graph.
The colour for the means created by stat_summary is set to black; otherwise it would be red and blue like the individual data lines. However, it is not possible to set more than one colour - so color=c("black", "blue") does not work.
I've already tried scale_colour_manual as explained here, but this will change the colours of the individual data lines, leaving the mean lines unaffected.
Any suggestion how to solve this? Code and data here.