title: Remove "floating" axis labels in facet_wrap plot?
body: <p>Using facet_wrap in ggplot2 to create a grid, but I have an uneven number of panels so the last row is incomplete. At the bottom of the last, blank panel is the axis ticks and text. Is it possible to shift this axis up (giving the last facet in each column the appearance of having applied free_x)? If not, can I remove it altogether as is seen below?</p>
  
  <p>To clarify with examples, this is what I'm getting:
  <a href="http://sape.inf.usi.ch/sites/default/files/ggplot2-facet-wrap.png" rel="nofollow noreferrer">http://sape.inf.usi.ch/sites/default/files/ggplot2-facet-wrap.png</a></p>
  
  <p><img src="https://i.stack.imgur.com/jzegM.png" alt="enter image description here"></p>
  
  <p>I desire something seen here (though, ideally with axis labelling on the facet in column 4):
  <a href="https://stackoverflow.com/questions/11979017/changing-facet-label-to-math-formula-in-ggplot2">Changing facet label to math formula in ggplot2</a></p>
  
  <p><img src="https://i.stack.imgur.com/SkzSS.png" alt="enter image description here"></p>
  
  <p>Thanks for any ideas or insight!</p>