Efficiently determine where documents differ

[Richard]

Hello,

I have been using the difflib library to find where 2 large HTML
documents differ. The Differ().compare() method does this, but it is
very slow - atleast 100x slower than the unix diff command.

How can I efficiently determine where 2 documents differ in Python?
(Ideally I am after the positions rather the actual text, which is
what SequenceMatcher().get_opcodes() returns.)

Richard

 

[Gabriel Genellina]

I have been using the difflib library to find where 2 large HTML
documents differ. The Differ().compare() method does this, but it is
very slow - atleast 100x slower than the unix diff command.

Differ compares sequences of lines *and* lines as sequences of characters
to provide intra-line differences. The diff command only processes lines.
If you aren't interested in intra-line differences, use a SequenceMatcher
instead. Or, invoke the diff command using subprocess.Popen +
communicate.

 

[Richard]

Differ compares sequences of lines *and* lines as sequences of characters  
to provide intra-line differences. The diff command only processes lines.
If you aren't interested in intra-line differences, use a SequenceMatcher  
instead. Or, invoke the diff command using   subprocess.Popen +  
communicate.

thank you very much Gabriel! Passing a list of the document lines
makes the efficiency comparable to the diff command.
Richard