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Diffstat (limited to 'Doc/whatsnew/3.1.rst')
| -rw-r--r-- | Doc/whatsnew/3.1.rst | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/Doc/whatsnew/3.1.rst b/Doc/whatsnew/3.1.rst index c76fd68..2179bf7 100644 --- a/Doc/whatsnew/3.1.rst +++ b/Doc/whatsnew/3.1.rst @@ -81,6 +81,28 @@ Support was also added for third-party tools like `PyYAML <http://pyyaml.org/>`_ PEP written by Armin Ronacher and Raymond Hettinger. Implementation written by Raymond Hettinger. +Since an ordered dictionary remembers its insertion order, it can be used +in conjuction with sorting to make a sorted dictionary:: + + >>> # regular unsorted dictionary + >>> d = {'banana': 3, 'apple':4, 'pear': 1, 'orange': 2} + + >>> # dictionary sorted by key + >>> OrderedDict(sorted(d.items(), key=lambda t: t[0])) + OrderedDict([('apple', 4), ('banana', 3), ('orange', 2), ('pear', 1)]) + + >>> # dictionary sorted by value + >>> OrderedDict(sorted(d.items(), key=lambda t: t[1])) + OrderedDict([('pear', 1), ('orange', 2), ('banana', 3), ('apple', 4)]) + + >>> # dictionary sorted by length of the key string + >>> OrderedDict(sorted(d.items(), key=lambda t: len(t[0]))) + OrderedDict([('pear', 1), ('apple', 4), ('orange', 2), ('banana', 3)]) + +The new sorted dictionaries maintain their sort order when entries +are deleted. But when new keys are added, the keys are appended +to the end and the sort is not maintained. + PEP 378: Format Specifier for Thousands Separator ================================================= |