Thursday, March 19, 2009
AS3/Flex - Find the minimum or maximum value for a specific node
While there are built in methods of sorting by a specific node in an XML file (using Sort, SortField, and the refresh function in ListCollectionView), it often fails to accomplish the task of sorting. I have found AS3's Array.sort and Array.sortOn to be more reliable when sorting numeric elements.
Given the following XML (save as test.xml):
<?xml version="1.0" encoding="utf-8?>
<rows>
<row>
<Department>DEPT 02</Department>
<Element1>294</Element1>
<Element2>244</Element2>
</row>
<row>
<Department>DEPT 00</Department>
<Element1>300</Element1>
<Element2>851</Element2>
</row>
<row>
<Department>DEPT 01</Department>
<Element1>325</Element1>
<Element2>465</Element2>
</row>
<row>
<Department>DEPT 05</Department>
<Element1>5464</Element1>
<Element2>545</Element2>
</row>
<row>
<Department>DEPT 04</Department>
<Element1>348</Element1>
<Element2>546</Element2>
</row>
</rows>
Find the maximum or minimum value for the node "Element1" or "Element2". Here's one way to do it using the sort function.
private function findValue(xmlData:XMLList, nodeName:String, options:Object=null):String
{
var coll:XMLListCollection = new XMLListCollection(xmlData.row[nodeName]);
var tmp:Array = new Array();
for(var i:int = 0; i < coll.children().length(); i++)
{
tmp.push(coll[i]);
}
var sorted:Array = tmp.sort(options);
return sorted[0];
}
Usage:
trace("MAX Element1: " + findValue(xml, "Element1", Array.DESCENDING|Array.NUMERIC));
trace("MAX Element2 " + findValue(xml, "Element2", Array.DESCENDING|Array.NUMERIC));
trace("MIN Element1: " + findValue(xml, "Element1", Array.NUMERIC));
trace("MIN Element2: " + findValue(xml, "Element2", Array.NUMERIC));
Output:
MAX SUBMITTED: 5464
MAX FILLED: 851
MIN SUBMITTED: 294
MIN FILLED: 244
Example MXML:
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" creationComplete="init()">
<mx:Script>
<![CDATA[
import mx.collections.XMLListCollection;
import mx.rpc.events.FaultEvent;
import mx.rpc.events.ResultEvent;
import mx.rpc.http.HTTPService;
private function init():void
{
// load xml
var service:HTTPService = new HTTPService();
service.resultFormat = HTTPService.RESULT_FORMAT_E4X;
service.url = "test.xml";
service.addEventListener(ResultEvent.RESULT, resultHandler);
service.addEventListener(FaultEvent.FAULT, errHandler);
service.send();
}
private function resultHandler(evt:ResultEvent):void
{
var xml:XMLList = new XMLList(evt.result);
trace("MAX Element1: " + findValue(xml, "Element1", Array.DESCENDING|Array.NUMERIC));
trace("MAX Element2 " + findValue(xml, "Element2", Array.DESCENDING|Array.NUMERIC));
trace("MIN Element1: " + findValue(xml, "Element1", Array.NUMERIC));
trace("MIN Element2: " + findValue(xml, "Element2", Array.NUMERIC));
}
private function findValue(xmlData:XMLList, nodeName:String, options:Object=null):String
{
var coll:XMLListCollection = new XMLListCollection(xmlData.row[nodeName]);
var tmp:Array = new Array();
for(var i:int = 0; i < coll.children().length(); i++)
{
tmp.push(coll[i]);
}
var sorted:Array = tmp.sort(options);
return sorted[0];
}
private function errHandler(evt:FaultEvent):void
{
trace(evt.fault.message);
}
]]>
</mx:Script>
</mx:Application>
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