[R] Plotting does odd line thing

[Jim Lemon]

On 04/08/2014 12:20 PM, David Doyle wrote:
> Hello folks,
>
> When I use the lines function below it connects all my points but then
> draws a line back to the start point.  Any suggestions on what is going on??
>
> mydata<-read.csv("http://doylesdartden.com/R/test_data.csv", sep=",")
>
> attach(mydata)
>
> plot(EMD~Year,data=mydata, subset = Well.ID %in% c("MW-1", "D_EMD"),
> col=ifelse(D_EMD, "black", "red"), pch=ifelse(D_EDM, 19, 17), cex = 1.5)
>
> lines(EMD~Year)
>
Hi David,
While you will get what you expect with:

lines(EMD[1:39]~Year[1:39])

I would be unnecessarily obscure in suggesting it. Try this:

subset<-Well.ID %in% c("MW-1", "D_EMD")
lines(EMD[subset]~Year[subset])

You haven't selected the same points for the lines function as you have 
for the plot function.

Jim