For my cryptography hobby (old school cryptograms, not modern cypto), I wrote this to find frequencies of letter pairs. I don't know if it could be adapted. 

# 
# 
# my $input = shift;
# my $input = "peon bookkeeper";
my $input;
#print $input."\n";
while (<>) {
    $input = $_;
    @evenmatches = ($input =~ m/
                                (.{2}?)
                                (?{ #print $^N . " found at " . ($tmpp
+os = pos($input)) . "\n";
                                    $chars{$^N}++; 
                                  })
                               /xg);
    #print join(", ", @evenmatches)."\n";
    #print $#evenmatches + 1 ." matches found\n";
    
    #print $input."\n";
    pos($input) = 1;
    @oddmatches = ($input =~ m/
                                (.{2}?)
                                (?{ #print $^N . " found at " . ($tmpp
+os = pos($input)) . "\n";
                                    $chars{$^N}++; 
                                  })
                               /xg);
    #print join(", ", @oddmatches)."\n";
    #print $#oddmatches + 1 ." matches found\n";
}

print "frequency of '$_' is $chars{$_}\n"
    foreach (sort {$chars{$b} <=> $chars{$a}} keys %chars);
print "\n";    
print "frequency of '$_' is $chars{$_}\n"
    foreach (sort keys %chars);

[download]

I humbly seek wisdom.

In reply to Re: Regex Word Pairs by goibhniu
in thread Regex Word Pairs by logie17

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.