You did not clearly specify actual and desired results. But, this may get you started. 

#!/usr/bin/perl

use strict;
use warnings;
use feature 'say';
use Data::Dumper;

my %hash;

for my $line (<DATA>)
{
    chomp $line;
    next if ($line =~ /dG\s=\s(.*?)\s/);

    my @temp = split(/\s+/, $line);
    $hash{ $temp[1] } = $temp[4];
}

say Dumper( \%hash );

__DATA__
300     dG = -62.54   [initially -70.70] gi178893_M23263_rna_300-1 
1    G    0    2    0    1
2    A    1    3    0    2
3    A    2    4    0    3
4    U    3    5    0    4
5    U    4    6    0    5
6    C    5    7    0    6
7    C    6    8    0    7
8    G    7    9    34    8
9    G    8    10    33    9
10    C    9    11    0    10
11    G    10    12    32    11
12    G    11    13    31    12
13    A    12    14    0    13
14    G    13    15    30    14
15    A    14    16    29    15
16    G    15    17    28    16
17    A    16    18    27    17
18    A    17    19    26    18
19    C    18    20    25    19

[download]
neil@ettin ~/src/perltest $ ./foo.pl 
$VAR1 = {
          'G' => '28',
          'C' => '25',
          'A' => '26',
          'U' => '0'
        };

[download]

Neil Watson
watson-wilson.ca

In reply to Re: Key value pair in hash inside while loop by neilwatson
in thread Key value pair in hash inside while loop by newtoperlprog

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.