Hi AR and Ratazong,

Thanks for the links to modules. But for me, "mismatch" only means "replacement". There should be no insertions or deletions. It seems to me that the module checks for all types of mismatches. no?

Hi Eliya,

I think I understand the method, but I doubt its efficient for my case. I forgot to mention that I have to perform the same for about 2e7 lines. Do you think it would be faster if we obtain all possible substrings for all lines?

For sake of this discussion, lets assume the line length is 50 and substring to check for each line is 20. So what I did was to create 21 different patterns, with the last 20 patterns replacing each character with a "." for regexp wild character comparison.

Then, its pretty straightforward:

for ($i=0; $i < "total lines"; $i++) {
    for $p (keys %pattern) {
        if ( $line[$i] =~ m/$p/ ) {
            # match; do something and break loop with "last;"
        }
    }
}

[download]

In reply to Re^2: generating hash patterns for searching with one mismatch by cedance
in thread generating hash patterns for searching with one mismatch by cedance

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.