ggplot2 error “no layers in plot”

Question

I have seen the question already asked... and solved adding stat = \"identity\" to geom_bar. But in my case, this does not solve anything (I still

Answer 1

The error message is due to fact that you didn't save d+geom_line() as an object.

#Save ggplot() as object
d <- ggplot(data=data3, aes(x=MonthNB, y=Ptot, colour=StationNAME))

#Add to d geom_line() - this makes the plot to appear on the screen but not saved.
d + geom_line()

To save layer to object

d<-d+geom_line()
#No error message
d