Hi monks,

Please go easy on me... i'm just a beginner.

o.k - my problem is that I want to calculate how many times a 'G' or 'C' occurs on the 3rd position in a piece of DNA starting from the first base..
e.g.   CTCCGGATCTAT A C/G is present on 3/4 3rd positions = 75%.

i am struggling a bit. 


for ($i = 1; $i < @dna; $i++)     {

   if ($dna[$i+3] eq 'C')    {


          $counter++;

    }

   elsif ($dna[$i+3] eq 'G')   {

          $counter++;

   }

 }

[download]
I can't think how to get the code to loop to every third base! Any help greatly appreciated.

update (broquaint): title change (was for loops) and added formatting

In reply to Count every 3rd base occurence by Anonymous Monk

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.