code: function dataStatistics(datas, statisticType) {
      var dataNameMap = {};
  
      zrUtil.each(datas, function (data) {
          data.each(data.mapDimension('value'), function (value, idx) {
              // Add prefix to avoid conflict with Object.prototype.
              var mapKey = 'ec-' + data.getName(idx);
              dataNameMap[mapKey] = dataNameMap[mapKey] || [];
              if (!isNaN(value)) {
                  dataNameMap[mapKey].push(value);
              }
          });
      });
  
      return datas[0].map(datas[0].mapDimension('value'), function (value, idx) {
          var mapKey = 'ec-' + datas[0].getName(idx);
          var sum = 0;
          var min = Infinity;
          var max = -Infinity;
          var len = dataNameMap[mapKey].length;
          for (var i = 0; i < len; i++) {
              min = Math.min(min, dataNameMap[mapKey][i]);
              max = Math.max(max, dataNameMap[mapKey][i]);
              sum += dataNameMap[mapKey][i];
          }
          var result;
          if (statisticType === 'min') {
              result = min;
          }
          else if (statisticType === 'max') {
              result = max;
          }
          else if (statisticType === 'average') {
              result = sum / len;
          }
          else {
              result = sum;
          }
          return len === 0 ? NaN : result;
      });
  }
docs: FIXME 公用？ 
  @param {Array.<module:echarts/data/List>} datas
  @param {string} statisticType 'average' 'sum'
  @inner