option = {
  // 其他配置项...
  series: [{
    name: '访问来源',
    type: 'pie',
    radius: ['50%', '70%'], //大小设置
    center: ['50%', '60%'], //位置设置
    data: [
      {value: 335, name: '直接访问'},
      {value: 310, name: '邮件营销'},
      {value: 234, name: '联盟广告'},
      {value: 135, name: '视频广告'},
      {value: 1548, name: '搜索引擎'}
    ],
    label: {
      normal: {
        show: true,
        position: 'center',
        textStyle: {
          fontSize: '20',
          fontWeight: 'bold'
        }
      },
    }
  }]
};