I just glanced at the problem but I think you would have to create a new variable to replace the hline. What about adding some text annotation in the graph instead?
On Tuesday, September 26, 2017, 3:51:46 PM EDT, David Doyle <kydaviddo...@gmail.com> wrote: Hello everyone, I have a plot showing chloride concentrations for various point over time. I also have a dotted line that show the Secondary Maximum Contaminant Level (my screening limit) on the graphs at 250 mg/L. But I can not figure out how to include the dotted line / Secondary Maximum Contaminant Level in the legend. Any thoughts? My code is as following and is linked to my data on the net. Thank you in advance David #Loads the ggplot2 package. library(ggplot2) ##This loads your data from your worksheet MyData <-read.csv("http://doylesdartden.com/Stats/TimeSeriesExample.csv", sep=",") #Sets which are detections and nondetects MyData$Detections <- ifelse(MyData$D_Chloride ==1, "Detected", "NonDetect") #does the plot p <- ggplot(data = MyData, aes(x=Year, y=Chloride , col=Detections)) + geom_point(aes(shape=Detections)) + #sets the detect vs. non-detect colors scale_colour_manual(values=c("black","red")) + #sets the y scale and log base 10 scale_y_log10() + ##adds line geom_hline(aes(yintercept=250),linetype="dashed")+ #location of the legend theme(legend.position=c("right")) + #sets the line color, type and size geom_line(colour="black", linetype="dotted", size=0.5) + ylab("Chloride (mg/L)") ## does the graph using the Location IDs as the different Locations. p + facet_grid(Location ~ .) [[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. [[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.