take the official tutorial as an example, assume that there are six buttons outside the canvas, corresponding to each item in the xAxis.data. 
 Click a button to make the opposite column green. 
 how can I implement it? 
 do I need to myChart.setOption (option) again every time I change color? 
  var myChart = echarts.init(document.getElementById("main"));
        var option = {
            title: {
                text: "ECharts "
            },
            tooltip: {},
            legend: {
                data:[""]
            },
            xAxis: {
                data: ["","","","","",""]
            },
            yAxis: {},
            series: [{
                name: "",
                type: "bar",
                data: [5, 20, 36, 10, 10, 20]
            }]
        };
        myChart.setOption(option);
						