检查元素是否存在于元组的元组中 [英] Check if element exists in tuple of tuples

问题描述

我有一个看起来像元组的列表:

I have a list of tuples that look like :

CODES = (
    ('apple', 'reddelicious'),
    ('caramel', 'sweetsticky'),
    ('banana', 'yellowfruit'),
)

检查该元组中是否存在值的最佳方法是什么?例如，我希望能够说:

What's the best way to check if a value exists in that tuple? For example I want to be able to say:

'apple' in CODES

并获得True

推荐答案

您正在寻找 any() :

You are looking for any():

if any('apple' in code for code in CODES):
    ...

结合简单的生成器表达式，即可完成此任务.生成器表达式采用每个元组，如果包含'apple'，则生成True. any()然后在它请求的第一项返回True时返回True(否则为False).因此，这就是您想要的.它也读得很好-如果任何元组包含'apple' ，则.

Combined with a simple generator expression, this does the task. The generator expression takes each tuple and yields True if it is contains 'apple'. any() then returns True when the first item it requests returns True (otherwise, False). Hence this does what you want. It also reads nicely - if any of the tuples contain 'apple'.

如果您要执行大量操作并且需要性能，那么可能值得对所有值进行一组设置以使您快速执行此操作:

If you are doing this a massive number of times and need performance, then it might be worth making a set of all of the values to allow you to do this very quickly:

cache = set(itertools.chain.from_iterable(CODES)))

自然，构造它会很慢并且会占用内存，因此，除非您需要大量的性能并进行大量的成员资格检查，否则这不是一个好主意.

Naturally, constructing this will be slow and use memory, so it wouldn't be a good idea unless you need a lot of performance and will be doing a lot of membership checks.

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