On Dec 10, 4:12 am, [EMAIL PROTECTED] wrote: > On Mon, 8 Dec 2008 at 23:46, eliben wrote: > > This is about Python 2.5.2 - I don't know if there were fixes to this > > module in 2.6/3.0 > > > I think I ran into a bug with difflib.SequenceMatcherclass. > > Specifically, its ratio() method. The following: > > >SequenceMatcher(None, [4] + [10] * 500 + [5], [10] * 500 + [5]).ratio > > () > > > returns 0.0 > > > While the same with 500 replaced by 100 returns .99... something > > Looking at the code ofSequenceMatcherthere's some caching going on > > when the sequences are longer than 200 elements (and indeed, I can > > reproduce the bug above 200 but not below). Can anyone confirm that > > this misbehaves and suggest a workaround ? > > Python 2.5.2 (r252:60911, Sep 29 2008, 20:34:04) > [GCC 4.3.1] on linux2 > Type "help", "copyright", "credits" or "license" for more information.>>> > from difflib importSequenceMatcher > >>>SequenceMatcher(None, [4] + [10] * 500 + [5], [10] * 500 + > >>> [5]).ratio() > > 0.99900299102691925 >
Strange. I could reproduce the problem both on ActiveState Python 2.5.2 for Windows, and in the online Try Python evaluator: http://try-python.mired.org/ Eli -- http://mail.python.org/mailman/listinfo/python-list
