freekngeek:

First you have to decide/determine what the primary index is. For example, it might be the two character first column or it may be a combination of several columns. You don't give enough information to be sure. (Though your sample data structure indicates that you're using a single key.)

Lets suppose that the first and second column comprise your key--In that case, you could do something like:

my %data;
while (my $line=<$INPUT_FILE_HANDLE>) {
   my ($rectype, $testID, $dimX, $dimY, $polynomial)
      = parse_input_line($line);
   my $key = "$rectype:$testID";
   $data{$key} = {
      RecType    => $rectype, TestID => $testID,
      DIM        => [ $dimX, $dimY ],
      Polynomial => $polynomial,
   };
}
[download]

Note the square brackets on the DIM line: that's how you can place an array reference inside your hash.

Does this answer your question? I don't feel like I understand just what it is you're having difficulty with, so I just guessed. If you could provide a bit more detail, we can give better answers.

...roboticus

When your only tool is a hammer, all problems look like your thumb.