具有多个索引的Python Map（Dict）

问题描述

我正在寻找一个在两个不同索引下保存相同值的数据结构，我可以通过 访问数据。

I am looking for a data structure that holds the same values under two different indexes, where I can access the data by either one.

示例：

x = mysticalDataStructure()
x.add(1,'karl', dog)
x.add(2,'lisa', cat)

$ x[1].age
2
$ x['karl'].age
2
$ x[1].age = 4
$ x['karl'].age
4

是否有任何预先滚动，或什么是最好的方法来滚动我自己的（我需要通过索引访问（从0到n的数字增加1），并通过一个字符串）。

Is there anything prerolled, or what is the best approach to roll my own (I need access via an index (number going from 0 to n in increments of 1), and via a string).

collections.ordereddict 似乎没有快速随机访问通过这个位置，只要我看到我只能用迭代器走，直到我到达元素 i （我可以按正确的顺序插入）。

collections.ordereddict does not seem to have fast random access via the position, as far as I see I can only walk it with the iterator until I reach element i (I can insert in the right order).

推荐答案

class MultiKeyDict(object):

    def __init__(self, **kwargs):
        self._keys = {}
        self._data = {}
        for k, v in kwargs.iteritems():
            self[k] = v

    def __getitem__(self, key):
        try:
            return self._data[key]
        except KeyError:
            return self._data[self._keys[key]]

    def __setitem__(self, key, val):
        try:
            self._data[self._keys[key]] = val
        except KeyError:
            if isinstance(key, tuple):
               if not key:
                  raise ValueError(u'Empty tuple cannot be used as a key')
               key, other_keys = key[0], key[1:]
            else:
               other_keys = []
            self._data[key] = val
            for k in other_keys:
                self._keys[k] = key

    def add_keys(self, to_key, new_keys):
        if to_key not in self._data:
            to_key = self._keys[to_key]
        for key in new_keys:
            self._keys[key] = to_key


    @classmethod
    def from_dict(cls, dic):
        result = cls()
        for key, val in dic.items():
            result[key] = val
        return result

用法：

>>> d = MultiKeyDict(a=1, b=2)
>>> d['c', 'd'] = 3 # two keys for one value
>>> print d['c'], d['d']
3 3
>>> d['c'] = 4
>>> print d['d']
4
>>> d.add_keys('d', ('e',))
>>> d['e']
4
>>> d2 = MultiKeyDict.from_dict({ ('a', 'b'): 1 })
>>> d2['a'] = 2
>>> d2['b']
2

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