在Python中更改有序字典的顺序

Question

我有一个有序字典，想要更改其中的顺序。在下面的代码示例中，我想将第三个项目（people）及其值移动到第二个位置。因此，顺序将变为动物，人，食物，饮料。我该怎么做？

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

- speedyrazor

---

请参见此问题。我认为你无法像你希望的那样对字典进行排序，除非显式地重新定义顺序。 - bveb333

Answer 1

"OrderedDicts" 按照插入顺序排序。因此，您需要通过循环遍历原始对象中的 "key:value" 对来构建一个新的 OrderedDict。没有任何 "OrderedDict" 方法可以帮助您。

因此，您可以创建一个 "tuple" 来表示 "keys" 的想法顺序，然后遍历它以创建一个新的 "OrderedDict"。

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

或者更雄辩地说

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

- dannymilsom

Answer 2

你可以编写自定义函数（警告：这种方法可行但是不够优雅）：

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

- Selcuk

Answer 3

我认为你必须手动完成它：

>>> 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']

- DSM