获得从排序字典到另一个的第一个N个键对 [英] Get first N key pairs from an Ordered Dictionary to another one

问题描述

我有一个按值排序的有序字典（ OrderedDict ）。如何获得顶级（如25）键值并将其添加到新字典？
例如：我有这样的东西：

I have an ordered dictionary (OrderedDict) sorted by value. How can I get the top (say 25) key values and add them to a new dictionary? For example: I have something like this:

dictionary={'a':10,'b':20,'c':30,'d':5}
ordered=OrderedDict(sorted(dictionary.items(), key=lambda x: x[1],reverse=True))

现在已订购是一个有序字典，我想创建一个字典说，通过获取前2个最频繁的项目和他们的键：

Now ordered is an ordered dictionary, I want to create a dictionary, say by taking the top 2 most-frequent items and their keys:

frequent={'c':30,'b':20}

推荐答案

OrderedDict的主要目的是保留创建元素的顺序。
你想要的是 collections.Counter ，内置了最常见的功能：

The primary purpose of OrderedDict is retaining the order in which the elements were created. What you want here is collections.Counter, which has the n-most-frequent functionality built-in:

>>> dictionary={'a':10,'b':20,'c':30,'d':5}
>>> import collections
>>> collections.Counter(dictionary).most_common(2)
[('c', 30), ('b', 20)]

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