Extjs 从吞吐量堆叠条形图中，希望显示最小值、最大值和平均值

我已经创建了吞吐量堆积条形图 从这个图表中，我们想要得到最小值、最大值和平均值。并希望它显示在标签上。但是我想不出怎么做，有什么帮助吗

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这是我试图实现的一些代码。

我想出了如何获取值

this.globalVar=Ext.Array.flatte（tempSeries）
globalVar具有图表的系列和类别值

然后调用showStats（图表）函数

var chart = Ext.getCmp('mychart'); // chart object
field = Ext.getCmp('myFieldId2'); // Labelfield Id
field.text = chart.chartConfig.yField.maximum;

showStats: function(chart) {
var project_oid = this.getContext().getProject().ObjectID;
//var chart = this.down('#display_box').add(this.getChartConfig(project_oid));
this.timePeriod = Rally.util.DateTime.getDifference(this._endDate, this._startDate,'month');
if (this.timePeriod == 0){
    this.timePeriod = 1;
};
var average = Ext.Array.mean(chart.calculator.globalVar);
average = Ext.Number.toFixed(average, 2);
var stdDev = this.standardDeviation(average, chart.calculator.globalVar);   
stdDev = Ext.Number.toFixed(stdDev, 2);     
this.down('#averageId').setText("Average" + " " + average); 
this.down('#countId').setText("Count"+ Ext.Array.sum(chart.calculator.globalVar));  
this.down('#minId').setText("Minimum"+ Ext.Array.min(chart.calculator.globalVar));  
this.down('#maxId').setText("Maximum"+ Ext.Array.max(chart.calculator.globalVar));  
this.down('#stdDevId').setText("Standard Deviation"+ stdDev);                   
this.down('#myFieldId').setText("Summary Metrics" + "(Last"+ this.timePeriod + months"+ ")");   
},      
standardDeviation: function(average, values){
   var squareDiffs = values.map(function(value){
     var diff = value - average;
     var sqrDiff = diff * diff;
     return sqrDiff;
   });
  var avgSquareDiff = Ext.Array.mean(squareDiffs);
  var stdDev = Math.sqrt(avgSquareDiff);
  return stdDev;
},