From c40b25fd682ca48182d351c9b5089423fdcacb80 Mon Sep 17 00:00:00 2001 From: Terry Reedy Date: Wed, 10 Nov 2010 17:50:26 +0000 Subject: [PATCH] Issue 2986: document heuristic for 3.1 --- Doc/library/difflib.rst | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/Doc/library/difflib.rst b/Doc/library/difflib.rst index 433764c6c57..c9d1eee8802 100644 --- a/Doc/library/difflib.rst +++ b/Doc/library/difflib.rst @@ -35,6 +35,11 @@ diffs. For comparing directories and files, see also, the :mod:`filecmp` module. complicated way on how many elements the sequences have in common; best case time is linear. + **Heuristic:** To speed-up matching, items whose duplicates appear more than 1% of + the time in sequences of at least 200 items are treated as junk. This has the + unfortunate side-effect of giving bad results for sequences constructed from + a small set of items. An option to turn off the heuristic will be added to + Python 3.2. .. class:: Differ