title: ggsave(): Error in UseMethod("grid.draw") : no applicable method for 'grid.draw' applied to an object of class "character"
body: <p>I am trying to save a plot with <code>ggsave()</code>.  I enter the following:</p>
  
  <pre><code>library(ggplot2)
  
  Test = data.frame("X" = seq(1, 10, 1), "Y" = 2*seq(1, 10, 1))
  
  P = ggplot(
      Test, aes(x=X, y=Y))+
      geom_line()
  
  ggsave(P, "test.pdf", device = "pdf")
  </code></pre>
  
  <p>But get the error:</p>
  
  <pre><code>Saving 7 x 7 in image
  Error in UseMethod("grid.draw") : 
    no applicable method for 'grid.draw' applied to an object of class "character"
  </code></pre>