title: How to adjust title position in ggplot2
body: <p>Here is the code:</p>
  
  <pre><code>require(ggplot2)
  require(grid)
  # pdf("a.pdf")
  png('a.png')
  a &lt;- qplot(date, unemploy, data = economics, geom = "line") + opts(title='A')
  b &lt;- qplot(uempmed, unemploy, data = economics) + geom_smooth(se = F) + opts(title='B')
  c &lt;- qplot(uempmed, unemploy, data = economics, geom="path") + opts(title='C')
  grid.newpage()
  pushViewport(viewport(layout = grid.layout(2, 2)))
  vplayout &lt;- function(x, y) viewport(layout.pos.row = x, layout.pos.col = y)
  print(a, vp = vplayout(1, 1:2))
  print(b, vp = vplayout(2, 1))
  print(c, vp = vplayout(2, 2))
  dev.off()
  </code></pre>
  
  <p>And result:</p>
  
  <p><img src="https://i.stack.imgur.com/AYgxe.png" alt="enter image description here"></p>
  
  <p>While here is what I would like to have, i.e. to position titles near the top of y-axis:</p>
  
  <p><img src="https://i.stack.imgur.com/AmQk1.png" alt="enter image description here"></p>