input: 
@results = ();
$results[1] = 1;
$results[2] = 2;
$results[3] = 1;
$results[4] = 3;
$results[5] = 1;
$results[6] = 1;

output:
@resultsByCode = ();
$resultsByCode[1] = (1,3,5,6);
$resultsByCode[2] = (2);
$resultsByCode[3] = (4);