title: Set common xlabel for subplots on the same line
body: <p>I took a look to several discussions on the site and I can't find what I want. I want to set a common xlabel to 2 subplots on the same line like this :</p>
  
  <p><a href="https://i.stack.imgur.com/bJRdU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bJRdU.png" alt="enter image description here"></a> </p>
  
  <p>I tried set_xlabel(), text(), but for the first it didn't work, and for the second I can't put the text at the bottom center.</p>
  
  <p>And I would like to optimize the code, if someone knows how.</p>
  
  <p>My code : </p>
  
  <pre><code>plt.subplot(121)
  plt.barh(range(1, len(y)+1), y)
  plt.yticks([i+1.5 for i in range(7)], range(7))
  plt.xlim(0, xmax)
  
  plt.ylabel("Y label")
  
  plt.subplot(122)
  plt.barh(range(1, len(y2)+1), y2, color="r")
  plt.yticks([i+1.5 for i in range(7)], range(7))
  plt.xlim(0, xmax)
  </code></pre>