r.round(Math.random() * 100),
                        echarts.number.round(Math.random() * 400)
                    ]);
                }

                function renderItem(params, api) {
                    if (params.context.rendered) {
                        return;
                    }
                    params.context.rendered = true;

                    var points = [];
                    for (var i = 0; i < data.length; i++) {
                        points.push(api.coord(data[i]));
          