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I have the following problem. I changed some parts of a online articel.
Afterwards, other people start editing this online articel.

Now I'm trying program a code with python that identify, if the guys after me, changed something (and how much, measured in added/deleted characters) in the part I changed.

For expample: The Text was: Hello Wolrd! What happend today? Goodbye I changed the Text to: Hello Wolrd! What happend today? Today I wrote an exam. Goodbye The Guy after me edited: Hello Wolrd! What happend today? Today I wrote a math exam. Goodbye

Now, the code should identify, that she changed "n math" and give me out how much percentage of my edit she changed. In this case: About 20 %.

I start using "difflib", but now I'm figured out that the code makes no sense. My code did the following: With difflib, I figured out the places in the text I changed. @@ -1,4 +1,4 @@
Afterwards, I checked the lines the guy after me changed in the same way. @@ -1,6 +1,6 @@ . After this, I compared, if lines are the same (+ value equal - value). But now, I figured out, that this does not work out. If the guy after me start editing in the middel of my changed part.

Have anybody a clue, how to do it?

hello_world
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1 Answers1

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The diff match patch library (module diff_match_patch) produces a cleaner output and simpler to understand :

Taken from the official docs :

diff_main("Good dog", "Bad dog") => [(-1, "Goo"), (1, "Ba"), (0, "d dog")]

With the actual code :

from diff_match_patch import diff_match_patch
D = diff_match_patch()
D.diff_main("Good dog", "Bad dog")

a '-1' is a deletion

a '1' is a addition

a '0' means no change

See : https://code.google.com/p/google-diff-match-patch/wiki/API

Pierre Alex
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  • I tried to use diff_main. But there occured the error, 'module' object has no attribute 'diff_main' – hello_world Dec 16 '14 at 14:14
  • Thanks,getting this right. I have a better view of changes. Then I can identify what I changes and what the guy after me changed. But how can I figure out if the guy after me changed something I changed before? – hello_world Dec 16 '14 at 14:51