教你如何在Flex Chart中画移动平均线

private function getMACollection(collection:ArrayCollection, offset:int):ArrayCollection
　{
　var newCollection:ArrayCollection = new ArrayCollection();
　var len:int = collection.length;
　for (var i:int = 0; i < len - offset + 1; i++)
　{
　var sumClose:Number = 0;
　for (var j:int = i ; j < offset + i; j++)
　{
　var o:Object = collection.getItemAt(j);
　sumClose += o.stockA;
　}
　var item:Object = new Object();
　item.date = collection.getItemAt(i + offset - 1).date;
　item.stockA = sumClose/offset;
　newCollection.addItem(item);
　}
　return newCollection;
　}