Could you possible explain the first while loop: 
 my %data;
while (<DATA>) {
    next if /mcp/;
    chomp;
    my ($s, $n) = split;
    push @{ $data{$s} }, $n;
}

[download]
If my file I'm trying to read in is called rat_event, should I open it above, such as here: 
open(rat_event,"RAT_EVENT");
@rat_event = <rat_event>;

[download]
and then do: 
my %rat_event;
while <RAT_EVENT> {
# Same as above
}

[download]
Thanks for the help.

In reply to Re^2: Using a Hash Variable in an If Statement by Bama_Perl
in thread Using a Hash Variable in an If Statement by Bama_Perl

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.