echarts使用dataset绑定数据， dataView显示数据均为NaNecharts bar' }, { type: 'bar' }, { type: 'bar' } ], toolbox: { show: true, feature: { dataView: { show: true, readOnly: false }, magicType: { show: true, type: ['line配置项内容和展示

echarts使用dataset绑定数据， dataView显示数据均为NaN。请问是什么原因？只能用serial方式才能显示吗？

      option = {
    legend: {},
    tooltip: {},
    dataset: {
        dimensions: ['product', '2015', '2016', '2017'],
        source: [{
                product: 'Matcha Latte',
                '2015': 43.3,
                '2016': 85.8,
                '2017': 93.7
            },
            {
                product: 'Milk Tea',
                '2015': 83.1,
                '2016': 73.4,
                '2017': 55.1
            },
            {
                product: 'Cheese Cocoa',
                '2015': 86.4,
                '2016': 65.2,
                '2017': 82.5
            },
            {
                product: 'Walnut Brownie',
                '2015': 72.4,
                '2016': 53.9,
                '2017': 39.1
            }
        ]
    },
    xAxis: {
        type: 'category'
    },
    yAxis: {},
    // Declare several bar series, each will be mapped
    // to a column of dataset.source by default.
    series: [{
            type: 'bar'
        },
        {
            type: 'bar'
        },
        {
            type: 'bar'
        }
    ],
    toolbox: {
        show: true,
        feature: {
            dataView: {
                show: true,
                readOnly: false
            },
            magicType: {
                show: true,
                type: ['line', 'bar']
            },
            restore: {
                show: true
            },
            saveAsImage: {
                show: true
            }
        }
    }
};