title: reorder columns based on values in a particular row.
body: <p>I have the following data in a dataframe:</p>
  
  <pre><code>  aa bb  cc
  1 3 4 5
  2 5 4 3
  3 7 8 6 
  ..
  100 33 63 55
  </code></pre>
  
  <p>I need to reorder the columns based on the values in the last row. The result of this transformation would be:</p>
  
  <pre><code>  bb  cc  aa
  1 4  5  3
  2 4  3  5 
  3 8  6  7
  ...
  100 63 55 33
  </code></pre>