symbolSize设置相对标尺长度echarts scatter配置项内容和展示

我想设置的长度是以标尺长度为准，而symbolSize设置的单位貌似是像素

      app.title = '气泡图';

var data = [
    [
        [1650, 1, 48, 10, '污渍', 1],
        [1650, 96, 3300, 10, '污渍', 1],
        [1650, 195, 3300, 12, '污渍', 1],
        [1650, 534, 3300, 10, '污渍', 1],
        [488, 849.5, 10, 19, '污渍', 1]
    ]
];


option = {
    backgroundColor: new echarts.graphic.RadialGradient(0.3, 0.3, 0.8, [{
        offset: 0,
        color: '#f7f8fa'
    }, {
        offset: 1,
        color: '#cdd0d5'
    }]),
    title: {
        text: ''
    },
    legend: {
        right: 10,
        data: ['1']
    },
    xAxis: {
        splitLine: {
            lineStyle: {
                type: 'dashed'
            }
        },
        min: 0,
        max: 3600,
        splitNumber: 12,
        position: 'top',
    },
    yAxis: {
        splitLine: {
            lineStyle: {
                type: 'dashed'
            }
        },
        min: 0,
        max: 1000,
        splitNumber: 20,
        scale: true,
        inverse: true,
    },
    series: [{
        name: '1',
        data: data[0],
        type: 'scatter',
        symbolSize: function(data) {
            var a = data[2];
            var b = data[3];
            return [a, b];
        },
        symbol: 'rect',
        label: {
            emphasis: {
                show: true,
                formatter: function(param) {
                    return param.data[4];
                },
                position: 'top'
            }
        },
        itemStyle: {
            normal: {
                shadowBlur: 10,
                shadowColor: 'rgba(120, 36, 50, 0.5)',
                shadowOffsetY: 5,
                color: new echarts.graphic.RadialGradient(0.4, 0.3, 1, [{
                    offset: 0,
                    color: 'rgb(251, 118, 123)'
                }, {
                    offset: 1,
                    color: 'rgb(204, 46, 72)'
                }])
            }
        }
    }]
};