Hi - below similar approach used by yourself... key difference is that it handles the different 'levels' in which data is structured; ie. 'ID' (hash) - 'key1/key2' (hash-of-hash) - 'keyX-valY' (hash-of-hash-of-array). 
my %hash=('ID' => {
                  'key1' => [ "key1_val1", "key1_val2" ],
                  'key2' => [ "key2_val1", "key2_val2" ]
                  }
          );

foreach my $id (keys %hash ) {
    foreach my $keyno ( sort keys %{$hash{$id}} ) {
        for (my $keyvalno = 0; $keyvalno <= $#{$hash{$id}{$keyno}}; $k
+eyvalno++) {
            print "$id - $keyno - $hash{$id}{$keyno}[$keyvalno]\n";
        }
    }
}

[download]

In reply to Re: Massive expansion of a hash of arrays? by Sjakie
in thread Massive expansion of a hash of arrays? by Amblikai

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.