获取Python词典的子集 [英] Get a sub-set of a Python dictionary

问题描述

我有字典:

{'key1':1, 'key2':2, 'key3':3}

我需要将该词典的子集传递给第三方代码.它只需要一个包含键 ['key1'，'key2'，'key99'] 的字典，如果它得到另一个键(例如'key3')，它就会爆炸一团糟.有问题的代码不在我的控制范围内，所以我必须清理字典.

I need to pass a sub-set of that dictionary to third-party code. It only wants a dictionary containing keys ['key1', 'key2', 'key99'] and if it gets another key (eg 'key3'), it explodes in a nasty mess. The code in question is out of my control so I'm left in a position where I have to clean my dictionary.

将字典限制为一组键的最佳方法是什么?

What's the best, way to limit a dictionary to a set of keys?

鉴于示例字典和上面允许的键，我想要:

Given the example dictionary and allowed keys above, I want:

{'key1':1, 'key2':2}

推荐答案

In [38]: adict={'key1':1, 'key2':2, 'key3':3}
In [41]: dict((k,adict[k]) for k in ('key1','key2','key99') if k in adict)
Out[41]: {'key1': 1, 'key2': 2}

在Python3(或Python2.7或更高版本)中，您可以使用 dict-comprehension dict-comprehension 也是:

In Python3 (or Python2.7 or later) you can do it with a dict-comprehension too:

>>> {k:adict[k] for k in ('key1','key2','key99') if k in adict}
{'key2': 2, 'key1': 1}

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