如何按python dict的值排序？

Question

最初的数据是：

dict = {<User: user2>: {'diff': 48, 'alike': 1}, <User: user3>: {'diff': 42, 'alike': 2}, <User: user4>: {'diff': 45, 'alike': 1}, <User: user5>: {'diff': 43, 'alike':
 2}, <User: user6>: {'diff': 46, 'alike': 1}, <User: user7>: {'diff': 46, 'alike': 1}, <User: user8>: {'diff': 49, 'alike': 1}, <User: user9>: {'diff': 50, 'ali
ke': 0}, <User: user10>: {'diff': 46, 'alike': 1}, <User: user11>: {'diff': 37, 'alike': 3}, <User: user12>: {'diff': 50, 'alike': 0}, <User: user13>: {'diff':
50, 'alike': 0}, <User: user14>: {'diff': 50, 'alike': 0}, <User: user15>: {'diff': 50, 'alike': 0}, <User: user16>: {'diff': 50, 'alike': 0}, <User: user17>: {
'diff': 50, 'alike': 0}, <User: user18>: {'diff': 50, 'alike': 0}, <User: user19>: {'diff': 50, 'alike': 0}, <User: user20>: {'diff': 50, 'alike': 0}}

然后我把它分类：

^{pr2}$

如何按“diff”排序？在

Answer 1

sorted(your_list, key=lambda el: el["diff"])

key关键字参数应该是一个函数，它接受要排序的列表的元素，并返回排序比较中应该使用的值。lambda是{}的简写，也就是说，它定义了一个函数（有几个限制）。同样的一行可以这样写：

^{pr2}$

Answer 2

首先，您没有对dict排序，而是对dicts的列表进行排序，这是非常不同的事情，尤其是Python中的dict没有定义顺序。在

您可以使用^{}和^{}轻松完成此操作：

import operator
sorted_dicts = sorted(dicts, key=operator.itemgetter("diff"))

sorted()内置函数接受key关键字参数，这是一个接受该值并给出另一个值进行排序的函数。这里我们使用itemgetter()从dict中获取所需的值来进行排序。在

编辑：

鉴于你的改变，有两个答案，因为你不清楚。如果需要值列表，只需从原始dict中提取它们：

^{pr2}$

这和拿dict.values()一样简单。当然，在python2.x下，您将希望使用viewitems()或{}来获得良好的性能。在

如果你想对dict本身进行排序，那是另一回事，因为{}本身就是无序的。在

首先，我想指出，sorted(dict)不会产生您建议的输出-dict迭代键，而不是默认值：

users = {
    '<User: user10>': {'alike': 1, 'diff': 46},
    '<User: user11>': {'alike': 3, 'diff': 37},
    '<User: user12>': {'alike': 0, 'diff': 50},
    '<User: user13>': {'alike': 0, 'diff': 50},
    '<User: user14>': {'alike': 0, 'diff': 50},
    '<User: user15>': {'alike': 0, 'diff': 50},
    '<User: user16>': {'alike': 0, 'diff': 50},
    '<User: user17>': {'alike': 0, 'diff': 50},
    '<User: user18>': {'alike': 0, 'diff': 50},
    '<User: user19>': {'alike': 0, 'diff': 50},
    '<User: user20>': {'alike': 0, 'diff': 50},
    '<User: user2>': {'alike': 1, 'diff': 48},
    '<User: user3>': {'alike': 2, 'diff': 42},
    '<User: user4>': {'alike': 1, 'diff': 45},
    '<User: user5>': {'alike': 2, 'diff': 43},
    '<User: user6>': {'alike': 1, 'diff': 46},
    '<User: user7>': {'alike': 1, 'diff': 46},
    '<User: user8>': {'alike': 1, 'diff': 49},
    '<User: user9>': {'alike': 0, 'diff': 50}
}

print(sorted(users))

给我们：

['<User: user10>', '<User: user11>', '<User: user12>', '<User: user13>', '<User: user14>', '<User: user15>', '<User: user16>', '<User: user17>', '<User: user18>', '<User: user19>', '<User: user20>', '<User: user2>', '<User: user3>', '<User: user4>', '<User: user5>', '<User: user6>', '<User: user7>', '<User: user8>', '<User: user9>']

要生成已排序的dict，我们需要使用^{}：

import collections

users = {
    '<User: user10>': {'alike': 1, 'diff': 46},
    '<User: user11>': {'alike': 3, 'diff': 37},
    '<User: user12>': {'alike': 0, 'diff': 50},
    '<User: user13>': {'alike': 0, 'diff': 50},
    '<User: user14>': {'alike': 0, 'diff': 50},
    '<User: user15>': {'alike': 0, 'diff': 50},
    '<User: user16>': {'alike': 0, 'diff': 50},
    '<User: user17>': {'alike': 0, 'diff': 50},
    '<User: user18>': {'alike': 0, 'diff': 50},
    '<User: user19>': {'alike': 0, 'diff': 50},
    '<User: user20>': {'alike': 0, 'diff': 50},
    '<User: user2>': {'alike': 1, 'diff': 48},
    '<User: user3>': {'alike': 2, 'diff': 42},
    '<User: user4>': {'alike': 1, 'diff': 45},
    '<User: user5>': {'alike': 2, 'diff': 43},
    '<User: user6>': {'alike': 1, 'diff': 46},
    '<User: user7>': {'alike': 1, 'diff': 46},
    '<User: user8>': {'alike': 1, 'diff': 49},
    '<User: user9>': {'alike': 0, 'diff': 50}
}

print(collections.OrderedDict(sorted(users.items(), key=lambda x: x[1]["diff"])))

这给了我们：

OrderedDict([('<User: user11>', {'diff': 37, 'alike': 3}), ('<User: user3>', {'diff': 42, 'alike': 2}), ('<User: user5>', {'diff': 43, 'alike': 2}), ('<User: user4>', {'diff': 45, 'alike': 1}), ('<User: user10>', {'diff': 46, 'alike': 1}), ('<User: user7>', {'diff': 46, 'alike': 1}), ('<User: user6>', {'diff': 46, 'alike': 1}), ('<User: user2>', {'diff': 48, 'alike': 1}), ('<User: user8>', {'diff': 49, 'alike': 1}), ('<User: user20>', {'diff': 50, 'alike': 0}), ('<User: user9>', {'diff': 50, 'alike': 0}), ('<User: user13>', {'diff': 50, 'alike': 0}), ('<User: user19>', {'diff': 50, 'alike': 0}), ('<User: user12>', {'diff': 50, 'alike': 0}), ('<User: user18>', {'diff': 50, 'alike': 0}), ('<User: user15>', {'diff': 50, 'alike': 0}), ('<User: user14>', {'diff': 50, 'alike': 0}), ('<User: user17>', {'diff': 50, 'alike': 0}), ('<User: user16>', {'diff': 50, 'alike': 0})])

注意，这里我们必须使用lambda语句作为键参数，因为itemgetter()不幸的是，它不能为我们获得多个级别的项。在