title: Summing rows in Python Dataframe
body: <p>I just started learning Python so forgive me if this question has already been answered somewhere else. I want to create a new column called "Sum", which will simply be the previous columns added up.</p>
  
  <pre><code>Risk_Parity.tail()
  
      VCIT  VCLT  PCY     RWR     IJR     XLU     EWL
  Date                            
  2017-01-31  21.704155   11.733716   9.588649    8.278629    5.061788    7.010918    7.951747
  2017-02-28  19.839319   10.748690   9.582891    7.548530    5.066478    7.453951    7.950232
  2017-03-31  19.986782   10.754507   9.593623    7.370828    5.024079    7.402774    7.654366
  2017-04-30  18.897307   11.102380   10.021139   9.666693    5.901137    7.398604    11.284331
  2017-05-31  63.962659   23.670240   46.018698   9.917160    15.234977   12.344524   20.405587
  </code></pre>
  
  <p>The table columns are a little off but all I need is (21.70 + 11.73...+7.95)
  I can only get as far as creating the column <code>Risk_Parity['sum'] =</code> , but then I'm lost.</p>
  
  <p>I'd rather not do have to do <code>Risk_Parity['sum] = Risk_Parity['VCIT'] + Risk_Parity['VCLT']...</code></p>
  
  <p>After creating the sum column, I want to divide each column by the sum column and make that into a new dataframe, which wouldn't include the sum column. </p>
  
  <p>If anyone could help, I'd greatly appreciate it. Please try to dumb your answers down as much as possible lol. </p>
  
  <p>Thanks!</p>
  
  <p>Tom</p>