If i undertand your update correctly.....
Im actually looking at several of these keys: 213118_at, 456218_at, 279548_at. Each of these will be in the format: 
Affy:HG_U133A:ID_HERE:74:303;

[download]
With the obvious replacement of the middle id (key) value. The data in this format will again "probably" have a similar situation where multiple ids (values) as in my original example. Im after the id value that occurs most frequently, e.g ENSG00000123623. This has to be stored with the original key so I then know which key corresponds to the most abundant value. Im not at all interested in keeping the less frequent values, so these can be just dropped.
A bit of a mouthful I know, but its the way my head works.

MonkPaul.

In reply to Re^2: Counting hash values by MonkPaul
in thread Counting hash values by MonkPaul

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.