title: Pandas: change order of crosstab result
body: <p>How to change order in the result of <em>pd.crosstab</em>:</p>
  
  <pre><code>pd.crosstab(df['col1'], df['col2'])
  </code></pre>
  
  <p>I would like to be able to sort by:</p>
  
  <ul>
  <li>unique values of either <em>df['col1']</em> or <em>df['col2']</em> (cols/rows of the crosstab result)</li>
  <li>by marginal values (e.g. showing higher-count values of <em>df['col1']</em> closer to the top)</li>
  </ul>