ggplot2: How to specify multiple fill colors for points that are connected by lines of different colors
scale_fill_manual(), scale_shape_manual() and scale_colour_manual() can be used only if you have set fill=, shape= or colour= inside the aes().
To change colour just for the points you should add colour=group inside geom_point() call.
ggplot(data, aes(x=iv, y=dv, group=group,shape=group)) +
geom_line() + geom_point(aes(colour=group)) +
scale_shape_manual(values=c(19,20,21))+
scale_colour_manual(values=c("blue", "red","gray"))
