title: d3.js - Timestamp based on year and week
body: <p>I have a column with data year&amp;week. I would like to create a date axis based on this.</p>
  
  <p>when i try to format the date, it is not working</p>
  
  <p>I tried this:</p>
  
  <pre><code>var parseDate = d3.time.format("%Y-%W").parse;
  
  d3.csv("temperatures_groups_2.csv", function(error, data) {
      data.forEach(function(d,i) {
          d.timestamp = parseDate(d.timestamp);
          alert(d.timestamp);
          d.temperature = +d.temperature;
      }
  });
  </code></pre>
  
  <p>i get null when the alert executes. </p>
  
  <p>If i replace the same with d3.time.format("%Y-%m").parse, it works fine. It takes the month but not week no.</p>
  
  <p>The csv contains data like this</p>
  
  <p>timestamp,temperature
  2013-01,19.5
  2014-02,21.5
  2015-03,20.5
  2016-04,20.5
  2017-05,21.25</p>