将列表转换为具有多个变量的函数的输入的Pythonic方式 [英] Pythonic way of converting a list to inputs of a function of several variables

问题描述

由于不知道这一点，我开始感到有点愚蠢...

说我有两个变量的函数:

  def testfun(x，y):返回x * y 

现在我有一个值列表，例如 [2,3] ，我想将这些值作为值输入到函数中.最Python化的方法是什么?我想到了这样的东西:

  def listfun(X):X_as_strs = str(X).strip('[]')表达式='testfun({0})'.format(X_as_strs)返回eval(表达式) 

...但是它看起来非常不符合Python规范，无论如何我都不想处理字符串！是否有一种衬板(例如)会让我感觉到里面所有的刺痛和可爱(就像Python经常发生的那样)?我觉得这可能是一件疯狂的事……

解决方案

* 表示法将在这里为您服务.

  def testfun(x，y):返回x * ydef listfun(X):返回testfun(* X)>>>测试列表= [3,5]>>>listfun(测试列表)15>>>testfun(*测试列表)15 

* 表示法专门用于解压缩函数调用列表.我还没有看到它可以在任何其他上下文中使用，但是调用 testfun(* [3,5])等效于调用 testfun(3,5).

I'm beginning to feel a little dumb for not figuring this out...

say I have a function of two variables:

def testfun(x,y):
    return x*y

now I have a list of values, say [2,3], which I want to input as values into the function. What's the most Pythonic way to do this? I thought of something like this:

def listfun(X):
    X_as_strs = str(X).strip('[]')
    expression = 'testfun({0})'.format(X_as_strs)
    return eval(expression)

... but it looks very un-pythonic and I don't want to deal with strings anyway! Is there a one liner (e.g.) that will make me feel all tingly and cuddly inside (like so often happens with Python)? I have a feeling it could be something crazy obvious...

解决方案

The * notation will serve you well here.

def testfun(x,y):
    return x*y

def listfun(X):
    return testfun(*X)

>>> testlist = [3,5]
>>> listfun(testlist)
15
>>> testfun(*testlist)
15

The * notation is designed specifically for unpacking lists for function calls. I haven't seen it work in any other context, but calling testfun(*[3,5]) is equivalent to calling testfun(3,5).

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