Comparing two book chapters (text files)

Nick Matzke matzke at berkeley.edu
Thu Feb 5 04:38:57 CET 2009



Chris Rebert wrote:
> On Wed, Feb 4, 2009 at 5:20 PM, Nick Matzke <matzke at berkeley.edu> wrote:
>> Hi all,
>>
>> So I have an interesting challenge.  I want to compare two book chapters,
>> which I have in plain text format, and find out (a) percentage similarity
>> and (b) what has changed.
>>
>> Some features make this problem different than what seems to be the standard
>> text-matching problem solvable with e.g. difflib.  Here is what I mean:
>>
>> * there is no guarantee that single lines from each file will be directly
>> comparable -- e.g., if a few words are inserted into a sentence, then a
>> chunk of the sentence will be moved to the next line, then a chunk of that
>> line moved to the next, etc.
>>
>> * Also, there are cases where paragraphs have been moved around, sections
>> re-ordered, etc.  So it can't just be a "linear" match.
>>
>> I imagine this kind of thing can't be all that hard in the grand scheme of
>> things, but I couldn't find an easily applicable solution readily available.
>>  I have advanced beginner python skills but am not quite where I could do
>> this kind of thing from scratch without some guidance about the likely
>> functions, libraries etc. to use.
>>
>> PS: I am going to have to do this for multiple book chapters so various
>> software packages, e.g. for windows, are not really usable.
> 
> Though not written in Python, wdiff
> (http://www.gnu.org/software/wdiff/wdiff.html) might be a good
> starting point.


Wow -- this is actually amazingly effective.  And fast!   Simple to run 
from python & then use python to parse the output.

Thanks!
Nick


> 
> Cheers,
> Chris
> 

-- 
====================================================
Nicholas J. Matzke
Ph.D. student, Graduate Student Researcher
Huelsenbeck Lab
Center for Theoretical Evolutionary Genomics
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University of California, Berkeley

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http://chem.tufts.edu/AnswersInScience/RelativityofWrong.htm
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