Hi, To my knowledge, an excellent of ggplot with a second y-axis is
https://rpubs.com/MarkusLoew/226759 In this example, the author uses two colors for the two lines, but the line shapes are the same -- both are solid. Could each line have its own color as well as its own shape? For example, can I make the red line with the linetype "twodash", while the blue line with the linetype "solid"? For convenience, I copied the codes as follows. ######## p <- ggplot(obs, aes(x = Timestamp)) p <- p + geom_line(aes(y = air_temp, colour = "Temperature")) # adding the relative humidity data, transformed to match roughly the range of the temperature p <- p + geom_line(aes(y = rel_hum/5, colour = "Humidity")) # now adding the secondary axis, following the example in the help file ?scale_y_continuous # and, very important, reverting the above transformation p <- p + scale_y_continuous(sec.axis = sec_axis(~.*5, name = "Relative humidity [%]")) # modifying colours and theme options p <- p + scale_colour_manual(values = c("blue", "red")) p <- p + labs(y = "Air temperature [°C]", x = "Date and time", colour = "Parameter") p <- p + theme(legend.position = c(0.8, 0.9)) p ######## Thanks, John [[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.