I'm not entirely sure what you're trying to do - although here's a guess. It's not using hashes (associative arrays), but it could.

use Data::Dumper;

my $header = <DATA>;
my @cols_h = split /\t/, $header;

my @data;

while (<DATA>)
{
    chomp;
    my @info = split /\t/;
    push @data, \@info;
}

# uncomment this to see the data we have so far.
#print Dumper(\@data);

foreach (@data)
{
    my $avg = ($_->[2] + $_->[3]) / 2;
    push @$_, $avg
}

# uncomment this to see the data we have so far.
#print Dumper(\@data);

# at this point, each @data is an array of arrays.
# Each of the arrays contained in @data is "anonymous" (unnamed).
# These anonymous arrays have the four columns (0-3), and a fifth colu
+mn
# which is an average of columns 2 and 3 (zero-based).

__DATA__
ID_REF    IDENTIFIER    GSM29783    GSM29784
31307_at    L17325    77    788
31308_at    L17330    -777    -877
31309_r_at    U50277    7    8
31310_at    X52009    -7777    -887
31311_at    X61070    77777    88

[download]

In reply to Re^3: naming a variable with the datum from another variable by Tanktalus
in thread naming a variable with the datum from another variable by duncharris

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.