I haven't read about the concept (yet!) so I'm just commenting on your code.

Copying and manipulating those hashes in max_diff is going to be slow, lots of memory copies, and if I've understood correctly you don't need to do it that way. Wouldn't something like this give you the number you need?

sub max_diff {
...
my $count = 0;

for (keys %{$hash1}) {
    $count++ unless exists $hash2->{$_};
}
for (keys %{$hash2}) {
    $count++ unless exists $hash1->{$_};
}
return $count;

[download]

In reply to Re: Optimizing a naive clustering algorithm by RichardK
in thread Optimizing a naive clustering algorithm by BUU

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.