How to set the width of DataGridColumn dynamically?

Question

What I want to do is, load data from a text file and put into a DataGrid component, the fields of ech record in the text have fixed length, and are seperated by a space, like this:
personal.txt
50 Uvwxyz  Male    123456789
60 Hijklmn  Male    67890123456789
30 Abcdefg Male    123456789012345
40 Opqrst   Female 987654321012345678
the configuration file is column.xml:
<dgcolumn>
     <personal>
          <len>20</len>
          <title>Name</title>
     </personal>
     <personal>
          <len>3</len>
          <title>Age</title>
     </personal>
     <personal>
          <len>6</len>
          <title>Sex</title>
     </personal>
     <personal>
          <len>20</len>
          <title>IdNumber</title>
     </personal>
</dgcolumn>
First I load the column.xml into an arrColumn, then read the personal.txt and seperate the record by the width( "len" in the xml file ), and put the seperated fields into another arrField, set the arrayFld as the dataProvider of a DataGrid, thus, the title can be showed as the headerText of the DataGrid and the data can be loaded correctly.
private function handleComplete( event:Event ):void
     var arrField:Array = new Array();
     var arrFile:Array = loader.data.split(/\n/);
     for( var i:int = 0; i < arrColumn.length; i ++ )
          arrField[i] = convIcom( arrFile[i] );
     adgFile.dataProvider = arrField;
     trace( "The data has successfully loaded" );
private function convIcom( strRecord:String ):Object
     var key:String = null;
     var dataField:String = null;
     var offset:int = 0;
     var obj:Object = new Object();
     if( strRecord.length > 0 )
          for( var i:int = 0; i < arrColumn.length; i ++ )
               dataField = strRecord.substr( offset, arrColumn[i].len );
               key = arrColumn[i].title;
               obj[key] = dataField;
               offset += arrColumn[i].len + 1;
     return obj;
<mx:DataGrid x="10" y="100" width="400" id="dgFile" />
The problem is, the width of the DataGridColumn is average, how to set the column width by the length of each field? I can calculate the rate of each field ( field / fields ), but I don't know how to change the property of the DataGridColumn.width.
Thanks for helping.

Answer 1

In the above post, I pasted an old version of personal.txt, so I paste it again:
personal.txt
Uvwxyz  50 Male   123456789
Hijklmn 60 Male   67890123456789
Opqrst  40 Female 987654321012345678
Abcdefg 30 Male   123456789012345
And I have another question, when the data is loaded into the DataGrid, the fields of each record are ordered in alphabetical order ( the "Age" column will appear firstly, then "IdNumber", "Name", "Sex" ), not as the order in column.xml, how to make it keep the sequence of the xml file?
Thanks again.