Another way is to use map on the original array and set all the entries which you don't want to '', and filter those out lateron.. 
my @set = qw (AAAAAT ATCGAT TTTTTG GCCCCC GTGGGG);
my $lim = 0.75;
my $len = length $set[0];

print "BEFORE:",scalar(@set),"\n";

map  { ( ((tr/A//)/$len < $lim) &&
          ((tr/T//)/$len < $lim) &&
          ((tr/C//)/$len < $lim) &&
          ((tr/G//)/$len < $lim)    ) or $_ = '' } @set;

print "AFTER:",scalar(@set),"\n";

[download]
Now the @set contains:
$VAR1 = '';
$VAR2 = 'ATCGAT';
$VAR3 = '';
$VAR4 = '';
$VAR5 = '';

[download]

.:| If it can't be fixed .. Don't break it |:.

In reply to Re^2: Removing Poly-ATCG from and Array of Strings by aukjan
in thread Removing Poly-ATCG from and Array of Strings by monkfan

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.