title: Add extra spacing between a subset of plots
body: <p>I'm trying to output 6 figures into one image, in a 3x2 layout. I'd like to place extra space between the top row and the bottom two rows.  Is this possible using R? I've looked through the documentation for par and plot and can't seem to find an appropriate option.</p>
  
  <p>Here's some example code:</p>
  
  <pre><code>a = rnorm(100,100,10)
  b = rnorm(100,100,10)
  
  par(mfrow=c(3,2), oma=c(1,1,1,1), mar=c(2,2,2,2))
  hist(a)
  hist(b)
  plot(a,b)
  plot(a,b)
  plot(a,b)
  plot(a,b)
  </code></pre>
  
  <hr>
  
  <p>Here's what that code outputs:</p>
  
  <hr>
  
  <p><img src="https://i.stack.imgur.com/coEMA.png" alt="alt text"></p>
  
  <hr>
  
  <p>Here's what I'd like it to output (I modified this image in an external editor). Note the extra space between the top row and bottom rows.</p>
  
  <hr>
  
  <p><img src="https://i.stack.imgur.com/SyBtg.png" alt="alt text"></p>
  
  <hr>