I'm not sure how to do this in lattice, but here is an option with ggplot2.
library(ggplot2) set.seed(123) # Make sure the data has a variable that indicates # which group is red and which one is black DF <- data.frame(x = rnorm(10), y = rnorm(10), gr = rep(1:5, 2),endpoint = c(rep("Red_Group",5),rep("Black_Group",5))) p <- ggplot(DF,aes(x=x,y=y,group=gr)) p <- p+geom_line() p <- p + geom_point(aes(colour=endpoint)) # Manually specify that you want the colors to be black and red p <- p + scale_colour_manual("endpoint", c("Black_Group" = "black", "Red_Group" = "red")) p Best, Juliet On Thu, Aug 6, 2009 at 10:27 AM, Kito Palaxou<kitopala...@yahoo.com> wrote: > > Hi all, > > I have a data frame like this: > > DF <- data.frame(x = rnorm(10), y = rnorm(10), gr = rep(1:5, 2)) > > and I make the following xy-plot: > > library(lattice) > xyplot(y ~ x, data = DF, groups = gr, type = "b", col = 1) > > > Is it possible that the two points that belong to the same group specified by > DF$gr to have a different color -- that is for each pair of points connected > by the line, I want one to be black and the other red. I tried: > > xyplot(y ~ x, data = DF, groups = gr, type = "b", col = 1:2) > > > but it doen't work. Is there any solution for this?? > > Thanks a lot! > > Kito > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.