I have two continuous variables x and y, and I need to plot the points in different colors according to a third factor variable called DIAGNOSI (that is, according to the disease group these observations belong) and used this:
m<-qplot(
x = Qalb,
y = Kratio,
data = dataset,
color = dataset$DIAGNOSI
)
Then, there is an index whose optimal cutoff has been identified in 2.43, and this index is equal to y/x, so i need to add to the plot a line showing where this threshold is
i need the remaining code for this