[英]How to pass kwargs while using map function?
As above, I want to use map function to apply a function to a bunch of things and collect results in a list.如上所述,我想使用 map 函数将函数应用于一堆事物并将结果收集到列表中。 However, I don't see how can I pass kwargs to that function.
但是,我不知道如何将 kwargs 传递给该函数。
For concreteness:对于具体性:
map(fun, elements)
What about kwargs?夸格呢?
Use a generator expression instead of a map
.使用生成器表达式而不是
map
。
(fun(x, **kwargs) for x in elements)
eg例如
reduce(fun(x, **kwargs) for x in elements)
Or if you're going straight to a list, use alist comprehension instead:或者,如果您要直接查看列表,请改用列表理解:
[fun(x, **kwargs) for x in elements]
The question is already answered at Python `map` and arguments unpacking该问题已在Python `map` 和参数解包中得到解答
The map does not exactly support named variable, though can handle multiple variable based on position.地图并不完全支持命名变量,但可以根据位置处理多个变量。
Since Python 3 the standard map can list arguments of multi-argument separately从 Python 3 开始,标准映射可以单独列出多参数的参数
map(fun, listx, listy, listz)
It is though less convenient for variable length list of named variables, especially in presence of **kwargs
in the function signature.尽管命名变量的可变长度列表不太方便,尤其是在函数签名中存在
**kwargs
情况下。 You can, though, introduce some intermediate function to pack separately positional and named arguments.但是,您可以引入一些中间函数来分别打包位置和命名参数。 For one line solution with lambda see Python `map` and arguments unpacking If you are not proficient with lambda, you can go as below
对于使用 lambda 的一行解决方案,请参阅Python `map` 和参数解包如果您不精通 lambda,可以按照以下步骤操作
def foldarg(param):
return f(param[0], **param[1])
list(map(foldarg, elements))
where elements
is something like其中
elements
是这样的
[[[1,2], dict(x=3, y=4)],
[[-2,-2], dict(w=3, z=4)]]
For unnamed variables list you can also use itertools.starmap对于未命名的变量列表,您还可以使用 itertools.starmap
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