title: object array Group by an element?
body: <p>Please see this example: <a href="http://jsfiddle.net/minagabriel/nayS7/" rel="nofollow">JsFiddle</a> </p>
  
  <p>Question: I have the following <code>JSON Array</code></p>
  
  <pre><code>y= [ {"LngTrend":15,"DblValue":10,"DtmStamp":1358226000000},     
  {"LngTrend":16,"DblValue":92,"DtmStamp":1358226000000},    
  {"LngTrend":17,"DblValue":45,"DtmStamp":1358226000000},
  {"LngTrend":18,"DblValue":87,"DtmStamp":1358226000000},
  
  
  {"LngTrend":15,"DblValue":10,"DtmStamp":1358226060000},
  {"LngTrend":16,"DblValue":87,"DtmStamp":1358226060000},
  {"LngTrend":17,"DblValue":45,"DtmStamp":1358226060000},
  {"LngTrend":18,"DblValue":92,"DtmStamp":1358226060000} ]
  </code></pre>
  
  <p>I was trying to group these object by <code>DtmStamp</code> end up having something like this : </p>
  
  <pre><code> x =  [[1358226000000,10,92,45,87],[1358226060000,10,87,45,92], .......]
  </code></pre>
  
  <p>In other words: </p>
  
  <pre><code>x[0][0] = y[0].DtmStamp ;
  x[0][1] = y[0].LngTrend ;
  x[0][2] = y[1].LngTrend ;
  x[0][3] = y[2].LngTrend ; 
  x[0][4] = y[3].LngTrend ;
  </code></pre>
  
  <p>Unfortunately, it ends with something I don't want. </p>
  
  <p>Here is what I have tried so far: </p>
  
  <pre><code>   var dataTrendArray = [];
             $.each(x, function (index, value) {
                  var trendArray = [];
                  if (index % 4 == 0) {
                      trendArray.push(x[index].DtmStamp);
                      for (var i = 0; i &lt; 4; i++) {
                          index = eval(index + i);
                          trendArray.push(x[index].DblValue);
                      }
                  }
  
                 console.log(trendArray) ;
                  dataTrendArray.push(trendArray);
              });
  </code></pre>
  
  <p>Can someone help me get on the right path?</p>