I have many pairs of arrays that I need to compare for a simple set of criteria element by element. There is a premium on speed.

I have arrays that are something like: 
@a = qw(a b c b c);
@b = qw(a x c d d);

[download]
...and simply need to evaluate the first index position where a simple set of criteria are met (e.g., $a[3] ne $b[3] and $a[3] ne 'x' and b[3] ne 'x'). In my example, the correct answer would be element 3.

I've tried a variety of simple solutions of the form:

for(0..$#a){
      if($a[$_] eq $b[$_] and $a[$_] ne 'x' ){
             etc. etc.
      }elsif( ){

      }
}

[download]

etc. but that is absolutely clobbering performance (array sizes are on the order of 1000 elements, but I have approximately 1X10^12 pairs of arrays to compare (but not all in memory!).

Anyone have a suggestion?

In reply to speedy way to compare elements in pairs of arrays? by CaptainF

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.