python中有序字典的变序

Question

我有一本订好的词典，想更改个别的顺序。在下面的代码示例中，我希望项3（人员）及其值一起移动到位置2。所以顺序是动物，人，食物，饮料。我该怎么处理他的？

import collections

queue = collections.OrderedDict()

queue["animals"] = ["cat", "dog", "fish"]
queue["food"] = ["cake", "cheese", "bread"]
queue["people"] = ["john", "henry", "mike"]
queue["drinks"] = ["water", "coke", "juice"]

print queue

Answer 1

编辑：您可以编写一个自定义函数（警告，这是有效的，但非常快速和肮脏）：

编辑：修复了当您尝试向前移动时出现的错误

import collections

def move_element(odict, thekey, newpos):
    odict[thekey] = odict.pop(thekey)
    i = 0
    for key, value in odict.items():
        if key != thekey and i >= newpos:
            odict[key] = odict.pop(key)
        i += 1
    return odict

queue = collections.OrderedDict()

queue["animals"] = ["cat", "dog", "fish"]
queue["food"] = ["cake", "cheese", "bread"]
queue["people"] = ["john", "henry", "mike"]
queue["drinks"] = ["water", "coke", "juice"]
queue["cars"] = ["astra", "focus", "fiesta"]

print queue

queue = move_element(queue, "people", 1)

print queue

Answer 2

OrderedDicts按insertion order排序。因此，您必须通过循环原始对象中的key:value对来构造新的OrderedDict。没有OrderedDict方法可以帮助您。

因此，您可以创建一个tuple来表示keys的思想顺序，然后遍历它来创建一个新的OrderedDict。

key_order = ('animal', 'people', 'food', 'drink')
new_queue = OrderedDict()
for k in key_order:
    new_queue[k] = queue[k]

或者更有说服力

OrderedDict((k, queue[k]) for k in key_order)

Answer 3

我想你得手动操作：

>>> keys = list(queue)
>>> keys
['animals', 'food', 'people', 'drinks']
>>> keys[1], keys[2] = keys[2], keys[1]
>>> queue = collections.OrderedDict((key, queue[key]) for key in keys)
>>> list(queue)
['animals', 'people', 'food', 'drinks']