title: convert string into numeric data in the dataframe using python
body: <p>If we have field like in the dataframe</p>
  
  <pre><code>A12
  A13
  A13
  A12
  A14
  </code></pre>
  
  <p>We need to convert this string into</p>
  
  <pre><code>A12   1
  A13   2
  A13   2
  A12   1
  A14   3
  </code></pre>