title: Pandas plot, combine two plots
body: <p>Currently I have 3 plots that I am plotting in the 2x2 subplots. It looks like this:</p>
  
  <pre><code>fig, axes = plt.subplots(nrows=2, ncols=2)
  df1.plot('type_of_plot', ax=axes[0, 0]);
  df2.plot('type_of_plot', ax=axes[0, 1]);
  df3.plot('type_of_plot', ax=axes[1, 0]);
  </code></pre>
  
  <p>The 4-th subplot is empty, and I would like the 3-rd one to occupy the whole last row.</p>
  
  <p>I tried various combinations of axes for the third subplot. Like <code>axes[1]</code>, <code>axes[1:]</code>, <code>axes[1,:]</code>. But everything results in the error.</p>
  
  <p>So how can I achieve what I want?</p>