if else condition in ggplot to add an extra layer

Question

say I want to plot two layers in ggplot, one containing points and another one containing lines if a certain criteria is fulfilled.

The code without the criteria cou

Answer 1

What you are seeing is a syntax error. The most robust way I can think of is:

tmp.data<-c(1,2,3) 
if(tmp.data[1]!="no value") {
   p = p + geom_point()
}
p + geom_line()

So you compose the object p in a sequence, only adding geom_point() when the if statements yields TRUE.