title: Sum of specific rows in a dataframe (Pandas)
body: <p>I'm given a set of the following data:</p>
  
  <pre><code>week  A      B      C      D      E
  1     243    857    393    621    194
  2     644    576    534    792    207
  3     946    252    453    547    436
  4     560    100    864    663    949
  5     712    734    308    385    303
  </code></pre>
  
  <p>I’m asked to find the sum of each column <strong>for specified rows/a specified number of weeks</strong>, and then plot those numbers onto a bar chart to compare A-E.</p>
  
  <p>Assuming I have the rows I need (e.g. <code>df.iloc[2:4,:]</code>), what should I do next? My assumption is that I need to create a mask with a single row that includes the sum of each column, but I'm not sure how I go about doing that.</p>
  
  <p>I know how to do the final step (i.e. <code>.plot(kind='bar'</code>), I just need to know what the middle step is to obtain the sums I need.</p>