Save ggplot within a function

Question

I\'m trying to save a ggplot within a function using graphics devices. But I found the code produces empty graphs. Below is a very very simple example.

libr         


        

Answer 1

These plots have to be printed:

ff <- function(){
  jpeg("a.jpg")
  p <- qplot(1:20, 1:20)
  print(p)
  dev.off()
}
ff()

This is a very common mistake.