i have data frame this bp r2 log10 96162057 0.2118000 2.66514431 96162096 0.0124700 0.31749391 96162281 0.0008941 0.07012148 96163560 0.5011000 2.48505399 96163638 0.8702000 3.37778598 and want plot bp against log10, , color points r2. r2 continuous values 0-1. myplot <- read.cvs("mytable.csv",head=true) attach(myplot) ggplot(myplot,aes(bp,log10, color=r2)) + geom_point() so far, good. display r2 colors in manually selected intervals , colors, (if had discrete values). ggplot(myplot,aes(bp,log10, color=r2)) + geom_point() + scale_color_manual(breaks= c("1","0.8","0.6","0.4","0.2","0"), values = c("red","yellow","green","lightblue","darkblue")) error: continuous value supplied discrete scale this looks pretty, rather set colors self. ggplot(myplot,aes(bp,log10, color=r2)) + geom_point(shape=1) + ...