python的可逆字典 [英] Reversible dictionary for python

问题描述

我想以类似于字典的形式在Python中存储一些数据： {1：'a'，2：'b'} 。每个值都将是独一无二的，而不仅仅是其他的值，而且在键之间。

I'd like to store some data in Python in a similar form to a dictionary: {1:'a', 2:'b'}. Every value will be unique, not just among other values, but among keys too.

有没有一个简单的数据结构可以用来获取相应的对象，无论是否请问使用键或值？例如：

Is there a simple data structure that I can use to get the corresponding object no matter if I ask using the 'key' or the 'value'? For example:

>>> a = {1:'a', 2:'b'}
>>> a[1]
'a'
>>> a['b']
2
>>> a[3]
KeyError

'keys'是标准的python int，值是短（<256char）的字符串。

The 'keys' are standard python ints, an the values are short (<256char) strings.

我目前的解决方案是创建一个反转的字典，并在原始字典中找不到结果进行搜索： p>

My current solution is creating a reversed dictionary and searching it if I can't find a result in the original dictionary:

pointsreversed = dict((v, k) for k, v in points.iteritems())
def lookup(key):
    return points.get(key) or pointsreversed.key()

两倍的空间，这不是很大（我的字典可以达到几百百万），平均慢50％。

This uses twice as much space, which isn't great (my dictionaries can be up to a few hundred megs) and is 50% slower on average.

编辑：如几个答案，两个dache不会增加内存使用量，因为它只是字典，而不是内容中的重复。

as mentioned in a few answers, two dicts doesn't double memory usage, as it's only the dictionary, not the items within, that is duplication.

有没有解决方案可以改进这个？

Is there a solution that improves on this?

推荐答案

相关文章：

Python映射反向

Python 1:1 mappings

当然，如果所有值和键都是唯一的，你不能只使用一个字典，并且最初插入key：value和value：key？

Of course, if all values and keys are unique, couldn't you just use a single dictionary, and insert both key:value and value:key initially?

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