sort a Python dictionary by value

Posted 2020-08-25

首先要明确一点，Python的dict本身是不能被sort的，更明确地表达应该是“将一个dict通过操作转化为value有序的列表”

有以下几种方法：

1. 

import operator
x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}
sorted_x = sorted(x.items(), key=operator.itemgetter(1))
#sorted by value

sorted_x = sorted(x.items(), key=operator.itemgetter(0))
#sorted by key

 

2.

sorted(dict1, key=dict1.get)

3.

sorted(d.items(), key=lambda x: x[1])

4.

sorted([(value,key) for (key,value) in mydict.items()])

5. Use OrderedDict

>>> # 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)])