[How Can I Group My data?]

chart1 = new cfx.Chart();

chart1.getLegendBox().setVisible(false);

chart1.getAllSeries().setGallery(cfx.Gallery.Bubble);

   var items =[{"x":"M1", "batch no":13, "Weight":12},{"x":"M2", "batch no":32, "Weight":55},{"x":"M3", "batch no":55, "Weight":16},{"x":"M1", "batch no":17, "Weight":12}];

    chart1.setDataSource(items);

chart1.create(document.getElementById('ChartDiv1'));

 

How Can I Group json data "x" ?