title: how to get same date as one array
body: <p>I have an array,</p>
  
  <pre><code>data =[{"date":"12/1/12","value":21},
         {"date":"12/2/12","value":34},
         {"date":"12/1/12","value":36},
         {"date":"12/1/12","value":32},
         {"date":"12/2/12","value":1},
         {"date":"12/2/12","value":4},
         {"date":"12/2/12","value":3},]
  </code></pre>
  
  <p>i need to create another array like by retrieving values from the arrays,</p>
  
  <pre><code>data1=[{"date":"12/1/12","value":21},
         {"date":"12/1/12","value":36},
         {"date":"12/1/12","value":32}]
  
  data2 =[{"date":"12/2/12","value":3},
          {"date":"12/2/12","value":4},
          {"date":"12/2/12","value":1},
          {"date":"12/2/12","value":34}]
  </code></pre>