Not sure whether it is a scatterplot or just a plot with 3 lines. If it is the latter,
library(reshape2) matplot(acast(my.df, TIME~ID, value.var='X'), type='l', col=1:3, ylab='X', xlab='TIME') legend('bottomright', inset=.05, legend=LETTERS[1:3], pch=1, col=1:3) A.K. On Friday, December 5, 2014 5:45 PM, farnoosh sheikhi <farnoosh...@yahoo.com> wrote: Hi Arun, I hope you are doing well. I have a data set as follow: my.df <- data.frame(ID=rep(c("A","B","C"), 5), TIME=rep(1:5, each=3), X=1:5) I would like to get a scatterplot where x axis is Time (1,2,3,4,5) and y axis is X, but I want to have three lines separately for each ID. I basically want to tack each ID over time. Is this possible? Thanks a lot and Happy Holidays to you! ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.