[R] Adding non-data line to legend ggplot2 Maximum Contaminant Level
John Kane
jrkrideau at yahoo.ca
Sun Oct 1 12:44:03 CEST 2017
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 <kydaviddoyle at 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 ~ .)
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