title: R put together traditional plot and ggplot2
body: <p>I have 2 graphs, a map plotted with <code>ggplot2</code> like this: </p>
  
  <pre><code>w&lt;-ggplot()+
    geom_polygon(data=dep_shp.df, aes(x=long,y=lat,group=group,fill=classJenks))+
  
    #   scale_fill_gradient(limits=c(40, 100))+
    labs(title ="Classification de la proportion de producteurs par départements
         \n par la methode de jenks (2008)")+
    theme_bw()+
    coord_equal()
  </code></pre>
  
  <p>and a graph as object of type <code>classIntervals</code>  from the <code>classInt</code> library.</p>
  
  <p>I would like to put together this 2 graphs. I have tried:</p>
  
  <pre><code>vplayout &lt;- function(x, y) viewport(layout.pos.row = x, layout.pos.col = y)
  grid.newpage()
  pushViewport(viewport(layout = grid.layout(1, 2)))
  
  #creation
  print(u, vp = vplayout(1, 1))
  print(v, vp = vplayout(1, 2))
  </code></pre>
  
  <p>And something with <code>grid.arrange</code></p>
  
  <pre><code>grid.arrange(plot1, plot2, ncol=2)
  </code></pre>
  
  <p>but none of these work.</p>