title: Django query for mutliple time aggregations
body: <p>I have a table of: Location | date | value (X)</p>
  
  <p>I wish to produce summaries of a value (X) for a data set by day, week, month and year, for multiple locations, using the Django ORM, with a single query. e.g:</p>
  
  <pre><code>Location  | Mon | ... | Fri | Week Avg. | Month Avg. | Year Avg.
  Location1 | 0.5 | ... | 0.8 | 0.7       | 1.1        | 1.5
  Location2 | ....
  </code></pre>
  
  <p>Currently, I have to do this by multiple queries, one over days of the week, and then one each for the aggregations over the week, month and year.</p>
  
  <p>Is there a smart way to do this using a single query (without returning the year's full data from the database)?</p>
  
  <p>Thanks</p>