Python不在dict条件句中表现 [英] Python not in dict condition sentence performance

问题描述

有没有人知道有什么更好的思考速度和资源？链接到一些值得信赖的来源将不胜感激。

 如果键不在dictionary.keys（）中：
  

或

  dictionary.get（key）：
  




解决方案

d do

 如果键不在字典中：
  

因为diction被按键迭代。

其次，这两个语句不是等价的 - 第二个条件是如果相应的值为falsy（ 0 ，， [] 等），不仅仅是键不存在。

最后，第一种方法肯定更快，更多的是pythonic。函数/方法调用是昂贵的。如果您不确定， timeit 。

Does anybody know about what is better to use thinking about speed and resources? Link to some trusted sources would be much appreciated.

if key not in dictionary.keys():

or

if not dictionary.get(key):

解决方案

Firstly, you'd do

if key not in dictionary:

since dicts are iterated over by keys.

Secondly, the two statements are not equivalent - the second condition would be true if the corresponding values is falsy (0, "", [] etc.), not only if the key doesn't exist.

Lastly, the first method is definitely faster and more pythonic. Function/method calls are expensive. If you're unsure, timeit.

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