Typical language analysis goes with your Option #2. I think I'll submit a code snippet which I used on some texts to extend some Moby Project results.

I'm not sure what you'd accomplish with the Option #3. You say you want to find the most common substring, but then your #3 says you'd mask out all occurrences of the most common "word." Don't you need to solve the question before you can perform that work? And secondly, if you wanted the second-most-common substring, is masking out the topmost common substrings going to be what you want? 

off the record, heretofore, the officer found that in the
theater of war, one hath need of a weatherproof theory of games

[download]

Now, remove substring 'he' and you won't find 'the'. Remove 'of' and you won't find 'off'. Is this effect intentional in your search? (Sorry, I couldn't contrive an example with overlapping 5-character snippets.)

--
[ e d @ h a l l e y . c c ]

In reply to Re: Most common substring by halley
in thread Most common substring 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.