Looks to me like you could pack the data quite a bit. The tags seem to contain just four letters (ACTG) ... which means you need just two bits per letter, that's 34*2=68 bits per tag which fits into 9 bytes instead of the original 34. Not sure what's allowed in the Error_rate_In_ASCII, but it looks there's quite a bit less than 256 possible characters in each position. So you could pack these as well.

This way you can save quite a lot of space and the comparison of the packed strings will also be quicker. Assuming the number of Error_rates for each Tag is not too big, it might also be better to use 

$data{$packed_tag} .= $packed_rate . "\n";

[download]
instead of 
push @{$data{$packed_tag}}, $packed_rate;

[download]
which will also let you use DB_File or some other on disk hash without the overhead of the multilevel ones like DBM::Deep.

HTH, Jenda
Support Denmark!
Defend the free world!

In reply to Re: Memory Efficient Alternatives to Hash of Array by Jenda
in thread Memory Efficient Alternatives to Hash of Array by neversaint

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.