title: Create a string columns based on values of columns and index Pandas
body: <p>I have the following dataframe:</p>
  
  <pre><code>    A   B
  Tenor       
  1   15.1726 0.138628
  2   15.1726 0.147002
  3   15.1726 0.155376
  4   15.1726 0.163749
  5   15.1726 0.172123
  </code></pre>
  
  <p>I want to be able to create another column that has a string by concatenating the previous columns, including the index. For instance, first row of this new columns would be: <code>XXXX1XXXX15.1726XXXX0.138628</code></p>
  
  <p>How can I do that in Pandas? If I try to use <code>df[ColumnName]</code> in the string formula Pandas will always bring the index, which will mess up my string.</p>