测试值是否存在于多个列表中 [英] Test if value exists in several lists

问题描述

我想检查每个列表中是否都存在一个值.

I would like to check if a value exists in every list.

以下内容按预期返回True，但似乎不符合Python规范.

The following returns True as expected, but seems un-pythonic.

什么是正确/更优雅的方式?

What is the correct/more elegant way to do this?

a = [1 ,2]
b = [1, 3]
c = [1, 4]
d = [2, 5]

False in [True if 1 in l else False for l in [a, b, c, d]  ]

推荐答案

您可以使用 all 和生成器表达式:

all(1 in x for x in (a, b, c, d))

演示:

>>> a = [1 ,2]
>>> b = [1, 3]
>>> c = [1, 4]
>>> d = [2, 5]
>>> all(1 in x for x in (a, b, c, d))
False
>>> all(1 in x for x in (a, b, c))
True
>>>

除了更具可读性之外，此解决方案还更有效，因为它使用了惰性求值.它只会检查确定结果所需的尽可能多的项目.

In addition to being more readable, this solution is more efficient since it uses lazy-evaluation. It will only check as many items as is necessary to determine the result.

此外，从来没有充分的理由这样做:

Also, there is never a good reason to do:

True if 1 in l else False

或类似的东西，因为in已经返回了布尔结果.您只需要:

or something similar since in already returns a boolean result. All you need is:

1 in l

对于否定版本，请使用:

For the negated version, use:

1 not in l

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