datagrid numeric sort issues

[Arbitrager]

Looks like the only workarounds to this problem (that I've seen) have to do with tricking the datagrid header to sort numbers correctly (numerically)..

I'm doing things a little differently.. I have two custom buttons that I would like to handle my sorting. ( I have the datagrid header hidden for various reasons)

My first column is a list of "application names" which i would like to remain happyly sorting as strings.

My second column is a list of "total cost" that I would like to sort numerically.

I would like to use Array.NUMERIC but I only want to affect the "total cost" column.

So here is the question: How can I convert the "total cost" column of the datagrid to a float, and get it to sort numerically within the datagrid?

Here is the relevent code:

var arrApps:Array = convertNodeListToObjectArray(nlAppData);
oDataGrid.dataProvider = arrApps;

btnSortByApplication.onRelease = function(){ this._parent.SortByApplication() };
btnSortByTotal.onRelease = function(){ this._parent.SortByTotal() };


private function gridInit(){
    
    // Add Application Name Column to Bottom Grid
    newColumn = new DataGridColumn("n");
    newColumn.editable = false;
    newColumn.resizable = false;
    newColumn.sortable = false;
    newColumn.sortOnHeaderRelease = false;
    newColumn.width = 100;
    newColumn.fontWeight="bold";
    newColumn.textDecoration = "underline";
    newColumn.color = 0x0033CC;
    oDataGrid.addColumn(newColumn);

    //Add Total Column
    newColumn = new DataGridColumn("t");
    newColumn.editable = false;
    newColumn.resizable = false;
    newColumn.sortable = false;
    newColumn.sortOnHeaderRelease = false;
    newColumn.textAlign = "right";
    newColumn.width = 80;
    
    oDataGrid.addColumn(newColumn);
    oDataGrid.editable = false;


    }


//column "n" is the application names column
private function SortByApplication(){
        oDataGrid.sortItemsBy("n", "ASC"); 
        
    }
//column "t" is the total cost column that I would like to sort numerically
private function SortByTotal(){
        oDataGrid.sortItemsBy("t", "DESC"); 
             }

*note that right now.. it sorts, just not correctly on the total cost column.. everything else is working

Thanks!