title: How can I create different sized subplots when using host_subplot?
body: <p>This is a follow-up to my <a href="https://stackoverflow.com/questions/43381249/how-can-i-have-a-stacked-plot-with-a-shared-x-axis-and-multiple-y-axis-on-one-of">previous question</a>. The answer to that question showed the solution of using <code>host_subplot</code> a second time to produce the second graph, and is copied below for convenience.</p>
  
  <p>I attempted to use <a href="https://stackoverflow.com/a/35881382/391161">this answer</a>, but I got the error <code>Unknown property gridspec_kw</code> when trying to pass <code>gridspec_kw</code> to the <code>host_subplot</code> function.</p>
  
  <p><strong>How can I get differently sized subplots when one of the plots also has a double Y-axis using <code>host_subplot</code>?</strong></p>
  
  <pre><code>"""
  Parasite axis demo
  
  The following code is an example of a parasite axis. It aims to show a user how
  to plot multiple different values onto one single plot. Notice how in this
  example, par1 and par2 are both calling twinx meaning both are tied directly to
  the x-axis. From there, each of those two axis can behave separately from the
  each other, meaning they can take on separate values from themselves as well as
  the x-axis.
  """
  from mpl_toolkits.axes_grid1 import host_subplot
  import mpl_toolkits.axisartist as AA
  import matplotlib.pyplot as plt
  
  host = host_subplot(211, axes_class=AA.Axes)
  plt.subplots_adjust(right=0.75)
  
  par1 = host.twinx()
  par2 = host.twinx()
  
  offset = 60
  new_fixed_axis = par2.get_grid_helper().new_fixed_axis
  par2.axis["right"] = new_fixed_axis(loc="right",
                                      axes=par2,
                                      offset=(offset, 0))
  
  par2.axis["right"].toggle(all=True)
  
  host.set_xlim(0, 2)
  host.set_ylim(0, 2)
  
  host.set_xlabel("Distance")
  host.set_ylabel("Density")
  par1.set_ylabel("Temperature")
  par2.set_ylabel("Velocity")
  
  p1, = host.plot([0, 1, 2], [0, 1, 2], label="Density")
  p2, = par1.plot([0, 1, 2], [0, 3, 2], label="Temperature")
  p3, = par2.plot([0, 1, 2], [50, 30, 15], label="Velocity")
  
  par1.set_ylim(0, 4)
  par2.set_ylim(1, 65)
  
  host.legend()
  
  host.axis["left"].label.set_color(p1.get_color())
  par1.axis["right"].label.set_color(p2.get_color())
  par2.axis["right"].label.set_color(p3.get_color())
  
  ## How can I make this subplot only 1/3 as tall as the first one?
  host2 = host_subplot(212, axes_class=AA.Axes, sharex=host)
  host2.plot([0,1,2], [5,6,7])
  host2.set_title('Sharing X axis')
  
  plt.draw()
  plt.show()
  </code></pre>