Hi, Try:
ex2 <- function() { d <- data.frame(x=1:5,a=1:5,b=2:6,c=3:7) g <- ggplot(d, aes(x)) for (n in c("a","b","c")) { g <- g + geom_line(aes_string(y=n,colour=n)) } return(g) } A.K. On Monday, December 30, 2013 7:49 PM, Geoffrey <lordgeoff...@optusnet.com.au> wrote: I am trying add geom_line's using a loop but the nature of unevaluated parameters is causing me problems. This code works: ex <- function() { d <- data.frame(x=1:5,a=1:5,b=2:6,c=3:7) g <- ggplot(d, aes(x)) g <- g + geom_line(aes(y=a,colour=a)) + geom_line(aes(y=b,colour=b)) + geom_line(aes(y=c,colour=c)) return(g) } This code (not surprisingly) fails: ex2 <- function() { d <- data.frame(x=1:5,a=1:5,b=2:6,c=3:7) g <- ggplot(d, aes(x)) for (n in c("a","b","c")) { g <- g + geom_line(aes(y=n,colour=n)) } return(g) } I believe i want something like the failing code, but done right. I have two problems (at least in this code): #1 how do handle the parameter evaluation #2 is this the right thing to be even doing with geom_line() & aes() ? Geoff. ______________________________________________ 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.