function getDefaultLabel(data, dataIndex) {
    var labelDims = data.mapDimension('defaultedLabel', true);
    var len = labelDims.length;

    // Simple optimization (in lots of cases, label dims length is 1)
    if (len === 1) {
        return retrieveRawValue(data, dataIndex, labelDims[0]);
    }
    else if (len) {
        var vals = [];
        for (var i = 0; i < labelDims.length; i++) {
            var val = retrieveRawValue(data, dataIndex, labelDims[i]);
            vals.push(val);
        }
        return vals.join(' ');
    }
}
Update symbol properties
@param {module:echarts/data/List} data
@param {number} idx
@param {Object} [seriesScope]
@param {Object} [seriesScope.itemStyle]
@param {Object} [seriesScope.hoverItemStyle]
@param {Object} [seriesScope.symbolRotate]
@param {Object} [seriesScope.symbolOffset]
@param {module:echarts/model/Model} [seriesScope.labelModel]
@param {module:echarts/model/Model} [seriesScope.hoverLabelModel]
@param {boolean} [seriesScope.hoverAnimation]
@param {Object} [seriesScope.cursorStyle]
@param {module:echarts/model/Model} [seriesScope.itemModel]
@param {string} [seriesScope.symbolInnerColor]
@param {Object} [seriesScope.fadeIn=false]