On Fri, May 1, 2009 at 12:22 PM, MUHC-Research <villa...@dms.umontreal.ca> wrote: > > Dear R-users, > > I would have another question about the ggplot() function in the ggplot2 > package. > > All the examples I've read so far in the documentation make use of a single > neatly formatted data.frame. However, sometimes, one may be interested in > plotting on the same grid information or objects derived from two totally > different datasets and customize both displays. I still cannot tell how this > can be done using ggplot(). > > Here's an example. > > ############### > ## A very simple data.frame; > > my.data = data.frame(X1 = > as.factor(rep(1:2,c(4,4))),X2=c(4,3,5,2,6,2,3,5),X3=c(1:3,2,2:4,5)) ; > > ## Let's say I want to add the X^2 line to the plot; > > squared = data.frame(X=1:12,Y=((1:12)/2)^2) ; > > ## A scatterplot for my.data ; > > p = ggplot(my.data,aes(x=X2,y=X3,group=X1)) ; > p = p+geom_point(aes(colour=X1)) ; > > ############# > > How can "squared" be added to the plot? At first, I used > > p+geom_line(data=squared,aes(x=X,y=Y,group=1,colour="green")) ; > > but the plotted line is always blue! In fact, I can replace colour by any > character value and I will still get a blue line.
You have two alternatives: p + geom_line(data=squared,aes(x=X,y=Y,group=1,colour="squared")) + labs(colour = "Dataset") p + geom_line(data=squared,aes(x=X,y=Y,group=1), colour="green") see section 4.5.2 of the book for details. Hadley -- http://had.co.nz/ ______________________________________________ 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.