title: Pandas: Merging two Dataframe, add columns and delete duplicate rows
body: <p>I have two dataframes, let's say, material inventory reports, for Jan and Feb:</p>
  <p>January Report</p>
  <pre><code>code  description    qty_jan   amount_jan
  
  WP1   Wooden Part-1  1000      50000
  MP1   Metal Part-1   500       5000
  GL1   Glass-1        100       2500
  </code></pre>
  <p>February Report</p>
  <pre><code>code  description    qty_feb   amount_feb
  
  WP1   Wooden Part-1  1200      60000
  MP2   Metal Part-2   300       3000
  GL1   Glass-1        50        1250
  GL2   Glass-2        200       5000
  
  </code></pre>
  <p>To monitor the progress of each material inventory, I would like to merge two reports, as follows:</p>
  <pre><code>code  description    qty_jan   amount_jan    qty_feb   amount_feb
  
  WP1   Wooden Part-1  1000      50000         1200      60000
  MP1   Metal Part-1   500       5000          0         0   
  MP2   Metal Part-2   0         0             300       3000
  GL1   Glass-1        100       2500          50        1250
  GL2   Glass-2        0         0             200       5000 
  </code></pre>
  <p>Note: Materials that are not listed in a report, are considered zero stock.</p>
  <p>How to merge these two reports?</p>