离散值在日历中的应用echarts heatmap配置项内容和展示

离散值在日历中如何应用才能使得视觉映射有效？

      var categories = ["劣Ⅴ","Ⅴ", "Ⅳ", "Ⅲ", "Ⅱ", "Ⅰ"];
function getVirtulData(year) {
    year = year || '2017';
    var date = +echarts.number.parseDate(year + '-01-01');
    var end = +echarts.number.parseDate((+year + 1) + '-01-01');
    var dayTime = 3600 * 24 * 1000;
    var data = [];
        var categoryNum = categories.length - 1;
    for (var time = date; time < end; time += dayTime) {
        data.push([
            echarts.format.formatTime('yyyy-MM-dd', time),
            categories[Math.round(Math.random()*categoryNum)]
        ]);
    }
    return data;
}

option = {
    title: {
        top: 30,
        left: 'center',
        text: '离散值在日历中的应用'
    },
    tooltip : {},
    visualMap: {
      dimension:1,
        inRange: {
            color: ['black', 'red', 'orange', 'yellow', 'green', 'blue'],
            },
         outOfRange: {
                color: '#000'
         },
        type: 'piecewise',
        orient: 'horizontal',
        left: 'center',
    categories: categories,
        top: 65,
        textStyle: {
            color: '#000'
        }
    },
    calendar: {
        top: 120,
        left: 30,
        right: 30,    
        dayLabel: {
        nameMap: 'cn'
      },
        orient:'vertical',
        cellSize: ['auto', 13],
        range: ['2016-5-1','2016-12-31'],
        itemStyle: {
            normal: {borderWidth: 0.5}
        },
        yearLabel: {show: false}
    },
    series: {
        type: 'heatmap',
        coordinateSystem: 'calendar',
        data: getVirtulData(2016)
    }
};