查找值是否存在于多个列表中

问题描述：

我有4个列表，并且列表中的每个元素在这4个列表中都是唯一的.如何查找该值是否存在于列表之一中，并返回该值存在于哪个列表中?

I have 4 list and each element on the list are unique across the 4 list. How do I find if the value exist in one of the list and return which list it exist?

示例列表:

value = 'a'
a = ['a','b','c']
b = ['d','e','f']
d = ['g','h','i']
c = ['j','k','l']

我的预期输出是找到值的列表的名称: 对于上面的示例，我的预期输出将是:

My expected output is the name of the list where the value is found: For the example above my expected output would be:

答

鉴于您的更新问题，我们假设a, b, c, d变量在全局范围内

Given your updated question, let's assume the a, b, c, d variables are in the global scope

value = 'a'
a = ['a','b','c']
b = ['d','e','f']
d = ['g','h','i']
c = ['j','k','l']

w = next(n for n,v in filter(lambda t: isinstance(t[1],list), globals().items()) if value in v)
print(w)

产生

即包含value

如果变量在本地范围内，例如在函数中，您可以改用locals()

If the variables are in a local scope, e.g. within a function, you can use locals() instead

def f():
    a = ['a','b','c']
    b = ['d','e','f']
    d = ['g','h','i']
    c = ['j','k','l']
    w = next(n for n,v in filter(lambda t: isinstance(t[1],list), locals().items()) if value in v)
    print(w)

f()

产生

注意:您可能希望采用命名约定来定位特定的变量组，例如targ_作为前缀

Note: you might want to adopt a naming convention to target a specific group of variables, e.g. targ_ as a prefix

targ_a = ['a','b','c']
targ_b = ['d','e','f']
targ_d = ['g','h','i']
targ_c = ['j','k','l']
w = next(n for n,v in filter(lambda t: isinstance(t[1],list) and t[0].startswith('targ_'), globals().items()) if value in v)
print(w)

产生

targ_a

为了更详细地说明事情，让我们看一下globals()调用返回的内容.例如使用python shell

To explain things a bit more in detail, let's have a look at what the globals() call returns. For example using the python shell

Python 3.4.3 (default, Oct 14 2015, 20:28:29) 
[GCC 4.8.4] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> value = 'a'
>>> targ_a = ['a','b','c']
>>> targ_b = ['d','e','f']
>>> targ_d = ['g','h','i']
>>> targ_c = ['j','k','l']
>>> globals()
{'targ_d': ['g', 'h', 'i'], 'targ_c': ['j', 'k', 'l'],
 '__builtins__': <module 'builtins' (built-in)>,
 '__doc__': None, '__package__': None,
 '__loader__': <class '_frozen_importlib.BuiltinImporter'>,
 'targ_a': ['a', 'b', 'c'], '__name__': '__main__',
 'targ_b': ['d', 'e', 'f'], '__spec__': None, 'value': 'a'}

如您所见，

globals()返回一个字典.它的键是在全局名称空间中定义的变量的名称.它的值就是每个这样的变量所保存的值.

as you can see, globals() returns a dictionary. Its keys are the names of the variables defined in the global namespace. Its values are the value held by each such variable.

因此

>>> next(n for n,v in filter(lambda t: isinstance(t[1],list) and t[0].startswith('targ_'), globals().items()) if value in v)
'targ_a'

在表达式生成的生成器上重复一次，该生成器在全局命名空间中生成每个名称，该名称对应于名称以targ_开头且包含等于value的元素的列表.通过对调用globals

iterates once on the generator produced by the expression, which yields each name in the global namespace that corresponds to a list whose name starts with targ_ and that contains an element equal to value. It does so by iterating on the dictionary returned by the call to globals

查找值是否存在于多个列表中

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