在 Python 中对字典（带有日期键）进行排序
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Sorting a dictionary (with date keys) in Python
提问by skyeagle
I have a dictionary. The keys are dates (datetime). I need to sort the dictionary so that the values in the dictionary are sorted by date - so that by iterating through the dictionary, I am processing items in the desired chronological (i.e. date/time) order.
我有一本字典。键是日期（日期时间）。我需要对字典进行排序，以便字典中的值按日期排序 - 这样通过遍历字典，我可以按所需的时间顺序（即日期/时间）处理项目。
How may I sort such a dictionary by date?
如何按日期对这样的字典进行排序？
Example:
例子：
mydict = { '2000-01-01': {fld_1: 1, fld_2: 42}, '2000-01-02': {fld_1:23, fld_2: 22.17} }
Note: I am using strings here instead of datetime, to keep the example simple
注意：我在这里使用字符串而不是日期时间，以保持示例简单
回答by Ignacio Vazquez-Abrams
Dictionaries are unsortable. Iterate over sorted(mydict.keys())instead.
字典是无法分类的。sorted(mydict.keys())而是迭代。
回答by foret
I'm sure that python knows how to compare dates. So:
我确信 python 知道如何比较日期。所以：
def sortedDictValues(adict):
items = adict.items()
items.sort()
return [value for key, value in items]
回答by SilentGhost
since your date strings seem to be in a proper format you could just do:
由于您的日期字符串似乎采用正确的格式，您可以这样做：
>>> sorted(mydict.items()) # iteritems in py2k
[('2000-01-01', {'fld_2': 42, 'fld_1': 1}), ('2000-01-02', {'fld_2': 22.17, 'fld_1': 23})]
回答by Jungle Hunter
Dictionaries never store anything in some order. But you can get a list of keys using d.keys()which could be sorted. Iterate over a generator like below.
字典从不以某种顺序存储任何东西。但是您可以获得d.keys()可以排序的键列表。迭代如下所示的生成器。
def sortdict(d):
for key in sorted(d): yield d[key]
Using this you will be able to iterate over values in chronological order.
使用它，您将能够按时间顺序迭代值。
for value in sortdict(mydict):
# your code
pass
回答by Dave Webb
If you're using Python 2.7+ or 3.1+ you could create an OrderedDictfrom collectionsfrom a sort of your dictionary and then iterate through that.
如果您使用的是 Python 2.7+ 或 3.1+，您可以从某种字典中创建一个OrderedDictfromcollections，然后遍历它。
ordered = OrderedDict(sorted(mydict.items(), key=lambda t: t[0]))
However, depending on what you want to do it's probably easier to iterate over a sorted list of keys from your dict.
但是，根据您想要执行的操作，从您的 dict 中迭代排序的键列表可能更容易。
回答by Tom Teman
Python 2.7 (released on July 3rd, 2010) supports an ordered dictionary type:
Python 2.7（2010 年 7 月 3 日发布）支持有序字典类型：
