Hi Marna, here is another example that should appear more similar to your scenario than my previous one.
x <- seq(1:100) y1 <- x*x g1 <- rep("y1", 100) df1 <- as.data.frame(cbind(x, y1), stringsAsFactors=FALSE) df1 <- as.data.frame(cbind(df1, g1)) colnames(df1)<- c("x", "value", "variable") y2 <- y1+1500 g2 <- rep("y2", 100) df2 <- as.data.frame(cbind(x, y2), stringsAsFactors=FALSE) df2 <- as.data.frame(cbind(df2, g2)) colnames(df2)<- c("x", "value", "variable") y3 <- y1+6000 g3 <- rep("y3", 100) df3 <- as.data.frame(cbind(x, y3), stringsAsFactors=FALSE) df3 <- as.data.frame(cbind(df3, g3)) colnames(df3)<- c("x", "value", "variable") avg <- (y1+y2+y3)/3 df4 <- as.data.frame(cbind(x, avg)) g4 <- rep("average", 100) df4 <- as.data.frame(cbind(df4, g4)) colnames(df4) <- c("x", "value", "variable") df <- data.frame(rbind(df1, df2, df3, df4)) # this is the data to start with ggplot() df # the df rows where the average value is stored sel <- which(df[,"variable"]=="average") library(ggplot2) ggplot(data = df[-sel,], aes(x=x, y=value, group=variable)) + geom_line() + geom_line(data = df[sel,], aes(x=x, y=value, group=variable), size=0.5, linetype="dashed", color="blue") Merry Christmas, -- GG [[alternative HTML version deleted]] ______________________________________________ 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.