title: pandas resample to get monthly average with time series data
body: <p>I'm using the time series dataset from tableau (<a href="https://community.tableau.com/thread/194200" rel="nofollow noreferrer">https://community.tableau.com/thread/194200</a>), containing daily furniture sales, and I want to resample to get average monthly sales. </p>
  
  <p>And I tried using resample in Pandas to get monthly mean:</p>
  
  <pre><code>There are four days in January selling furniture, 
  and there is no sales in the rest of Jan.
  
  Order Date   Sales
  ...
  2014/1/6     2573.82
  2014/1/7     76.728
  2014/1/16    127.104
  2014/1/20    38.6
  ...
  
  y_furniture = furniture['Sales'].resample('MS').mean()
  
  </code></pre>
  
  <p>I want the result to be the actual average sale per month. </p>
  
  <p>That is, all daily sales adding up and divided by 31 days, which is 90.85, but the code divided the summation by 4, which is around 704. This doesn't correctly reflect the actual monthly sales.</p>
  
  <p>Does anyone know how to solve this problem?</p>