问题：Python字典：keys（）和values（）总是相同的顺序吗？
看起来字典的keys()和values()方法返回的列表始终是一对一映射（假设在调用这两种方法之间字典没有改变）。
例如：
>>> d = {'one':1, 'two': 2, 'three': 3}
>>> k, v = d.keys(), d.values()
>>> for i in range(len(k)):
print d[k[i]] == v[i]
True
True
True
如果您没有在调用keys()和调用之间更改字典values()，那么假设上述for循环将始终显示True是否错误？我找不到任何证明文件。
It looks like the lists returned by keys() and values() methods of a dictionary are always a 1-to-1 mapping (assuming the dictionary is not altered between calling the 2 methods).
For example:
>>> d = {'one':1, 'two': 2, 'three': 3}
>>> k, v = d.keys(), d.values()
>>> for i in range(len(k)):
print d[k[i]] == v[i]
True
True
True
If you do not alter the dictionary between calling keys() and calling values(), is it wrong to assume the above for-loop will always print True? I could not find any documentation confirming this.
回答 0
发现了这一点：
如果items()，keys()，values()，
iteritems()，iterkeys()，和
itervalues()被称为中间没有修改的字典，列表会直接对应。
在2.x文档和3.x文档上。
Found this:
If items(), keys(), values(),
iteritems(), iterkeys(), and
itervalues() are called with no
intervening modifications to the
dictionary, the lists will directly
correspond.
On 2.x documentation and 3.x documentation.
回答 1
是的，您观察到的确实是一个有保证的属性-如果未更改dict，则keys（），values（）和items（）会以一致的顺序返回列表。iterkeys（）＆c也以与相应列表相同的顺序进行迭代。
Yes, what you observed is indeed a guaranteed property — keys(), values() and items() return lists in congruent order if the dict is not altered. iterkeys() &c also iterate in the same order as the corresponding lists.
回答 2
Yes it is guaranteed in python 2.x:
If keys, values and items views are iterated over with no intervening
modifications to the dictionary, the order of items will directly
correspond.
回答 3
回答 4
对文档的良好引用。无论文档/实现如何，都可以通过以下方法保证订单的准确性：
k, v = zip(*d.iteritems())
Good references to the docs. Here’s how you can guarantee the order regardless of the documentation / implementation:
k, v = zip(*d.iteritems())
回答 5
回答 6
就其价值而言，我编写的一些常用的生产代码都基于此假设，但我从未遇到过任何问题。我知道那不是真的:-)
如果您不想冒险，我会尽可能使用iteritems（）。
for key, value in myDictionary.iteritems():
print key, value
For what it’s worth, some heavy used production code I have written is based on this assumption and I never had a problem with it. I know that doesn’t make it true though :-)
If you don’t want to take the risk I would use iteritems() if you can.
for key, value in myDictionary.iteritems():
print key, value
回答 7
我对这些答案不满意，因为我想确保即使使用不同的字典，导出的值也具有相同的顺序。
在这里，您可以预先指定键顺序，即使字典更改，返回的值也将始终具有相同的顺序，或者您使用不同的字典。
keys = dict1.keys()
ordered_keys1 = [dict1[cur_key] for cur_key in keys]
ordered_keys2 = [dict2[cur_key] for cur_key in keys]
I wasn’t satisfied with these answers since I wanted to ensure the exported values had the same ordering even when using different dicts.
Here you specify the key order upfront, the returned values will always have the same order even if the dict changes, or you use a different dict.
keys = dict1.keys()
ordered_keys1 = [dict1[cur_key] for cur_key in keys]
ordered_keys2 = [dict2[cur_key] for cur_key in keys]
