title: Python: Scaling numbers column by column with pandas
body: <p>I have a Pandas data frame 'df' in which I'd like to perform some scalings column by column.</p>
  
  <ul>
  <li>In column 'a', I need the maximum number to be 1, the minimum number to be 0, and all other to be spread accordingly.</li>
  <li>In column 'b', however, I need the <strong>minimum number to be 1</strong>, the <strong>maximum number to be 0</strong>, and all other to be spread accordingly.</li>
  </ul>
  
  <p>Is there a Pandas function to perform these two operations? If not, numpy would certainly do.</p>
  
  <pre><code>    a    b
  A   14   103
  B   90   107
  C   90   110
  D   96   114
  E   91   114
  </code></pre>