title: Reassign labels of columns from 0 after drop of few columns
body: <p>I removed some duplicate columns by the following command. </p>
  
  <pre><code>columns = XY.columns[:-1].tolist()
  XY1 = XY.drop_duplicates(subset=columns,keep='first').
  </code></pre>
  
  <p>The result is below:</p>
  
  <blockquote>
  <pre><code>Combined Series shape :  (100, 4)                            
  Combined Series:     1    222  223          0                
  0    0    0    0  1998.850000                                
  1    0    0    0     0.947361
  2    0    0    0     0.947361
  3    0    0    0     0.947361
  4    0    0    0     0.947361
  </code></pre>
    
    <p>Now the columns is labelled 1 222 223 0 (0 label at the end is because of concat with another df !!)  I want the columns to be
    re-labelled from index 0 onwards. How'll I do it?</p>
  </blockquote>