瀑布图负数问题echarts category配置项内容和展示

瀑布图负数直接为负了，要的效果如图

      option = {
    title: {
        text: '阶梯瀑布图',
        subtext: ''
        
    },
    tooltip : {
        trigger: 'axis',
        axisPointer : {            // 坐标轴指示器，坐标轴触发有效
            type : 'shadow'        // 默认为直线，可选为：'line' | 'shadow'
        },
        formatter: function (params) {
            var tar;
            if (params[1].value != '-') {
                tar = params[1];
            }
            else {
                tar = params[0];
            }
            return tar.name + '<br/>' + tar.seriesName + ' : ' + tar.value;
        }
    },
    legend: {
        data:['支出','收入']
    },
    grid: {
        left: '3%',
        right: '4%',
        bottom: '3%',
        containLabel: true
    },
    xAxis: {
        type : 'category',
        splitLine: {show:false},
        data :  function (){
            var list = [];
            for (var i = 1; i <= 11; i++) {
                list.push('11月' + i + '日');
            }
            return list;
        }()
    },
    yAxis: {
        //type : 'value'
    },
    series: [
        {
            name: '辅助',
            type: 'bar',
            stack: '总量',
            itemStyle: {
                normal: {
                    barBorderColor: 'rgba(0,0,0,0)',
                    color: 'rgba(0,0,0,0)'
                },
                emphasis: {
                    barBorderColor: 'rgba(0,0,0,0)',
                    color: 'rgba(0,0,0,0)'
                }
            },
            data: [0, 900, 1245, 1530, 1376, 1376, 1511, 1689, 1856, 1495, 1292]
        },
        {
            name: '收入',
            type: 'bar',
            stack: '总量',
            label: {
                normal: {
                    show: true,
                    position: 'top'
                }
            },
            data: [-900, -345, -393, '-', '-', 135, 178, 286, '-', '-', '-']
        },
        {
            name: '支出',
            type: 'bar',
            stack: '总量',
            label: {
                normal: {
                    show: true,
                    position: 'bottom'
                }
            },
            data: ['-', '-', '-', 108, 154, '-', '-', '-', 119, 361, 203]
        }
    ]
};