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lib/Algorithm/RabinKarp.pm  view on Meta::CPAN

    warn "Possible match for 'needle' at @pos" 
      if $needle_hash eq $hay_hash;
  }
  
  
=head1 DESCRIPTION

This is an implementation of Rabin and Karp's streaming hash, as
described in "Winnowing: Local Algorithms for Document Fingerprinting" by
Schleimer, Wilkerson, and Aiken.  Following the suggestion of Schleimer,
I am using their second equation:

  $H[ $c[2..$k + 1] ] = (( $H[ $c[1..$k] ] - $c[1] ** $k ) + $c[$k+1] ) * $k

The results of this hash encodes information about the next k values in
the stream (hense k-gram.) This means for any given stream of length n
integer values (or characters), you will get back n - k + 1 hash
values.

For best results, you will want to create a code generator that filters
your data to remove all unnecessary information. For example, in a large