I need a way to calculate a "fingerprint" on a modest-sized text document that will allow matching this document to ones which are very similar (differing by formatting, perhaps a few small insertions, etc.). Specifically, I want to match up text-rendered web pages (we run the HTML through a text-mode browser like "lynx" and dump the output) which may be "nearly" identical (for example, news stories at multiple sites might be the same story from a wire service, with some minor formatting changes depending on whether the story is on one newspaper's website or another).

What we have tried so far is to do things like drop all small words (<= 5 characters), reduce to lower-case, and remove all whitespace, then checksum. That's fairly accurate, but it doesn't give me a "nearness" number. I'd like some reliable way of pointing at two different 10K text strings, and saying "string A is 99% likely to be the same article as string B". I've thought about using String::Approx for this, too. Haven't actually worked it up into a solution yet.

--
Jeff Boes
Database Engineer
Nexcerpt, Inc.
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In reply to Fingerprinting text documents for approximate comparison by Mur

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