Although this should be trivial, I'm having a spot of trouble. I want to make a lattice plot of the format y1+y2 ~ x | grp but then fit a lm to each y variable and add an abline of those models in different colors. If the xyplot followed y~x|grp I would write a panel function as below, but I'm unsure of how to do that with y1 and y2 without reshaping the data before hand. Thoughts appreciated. -Andy
foo <- data.frame(y1 = 1:25+rnorm(100, -3, 1), y2 = 1:25+rnorm(100,3,1), x = rep(1:25,4), grp = rep(letters[1:4],25)) # I want to add a trend line for y1 and y2 here: xyplot(y1+y2 ~ x | grp, data = foo) # like this example for just one y variable: xyplot(y1~x|grp, data = foo, panel = function(x,y) { lm1 = lm(y~x) panel.points(x,y, col = "red") panel.abline(lm1, col = "red") #lm2 = lm(y~x) # model for y2 #panel.points(x,y, col = "blue") #points for y2 #panel.abline(lm2, col = "blue") #abline for y2 }) > version _ platform i386-pc-mingw32 arch i386 os mingw32 system i386, mingw32 status major 2 minor 2.1 year 2005 month 12 day 20 svn rev 36812 language R ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html