Show example of how to make a sorted dictionary

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Raymond Hettinger 2009-11-10 19:35:55 +00:00
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@ -884,3 +884,25 @@ semantics pass-in keyword arguments using a regular unordered dictionary.
`Equivalent OrderedDict recipe <http://code.activestate.com/recipes/576693/>`_
that runs on Python 2.4 or later.
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.