如何在Python中将函数作为函数参数传递 [英] How to pass a function as a function parameter in Python

问题描述

这是我目前拥有的，并且工作正常:

This is what I currently have and it works fine:

def iterate(seed, num):
    x = seed
    orbit = [x]
    for i in range(num):
        x = 2 * x * (1 - x)
        orbit.append(x)
    return orbit

现在，如果我想将第5行的迭代方程式更改为x = x ** 2-3，则必须使用第5行以外的所有相同代码创建一个新函数.可以将函数用作参数的更通用的函数?

Now if I want to change the iterating equation on line 5 to, say, x = x ** 2 - 3, I'll have to create a new function with all the same code except line 5. How do I create a more general function that can have a function as a parameter?

推荐答案

功能是一等公民在Python.您可以将函数作为参数传递:

Functions are first-class citizens in Python. you can pass a function as a parameter:

def iterate(seed, num, fct):
#                      ^^^
    x = seed
    orbit = [x]
    for i in range(num):
        x = fct(x)
        #   ^^^
        orbit.append(x)
    return orbit

在您的代码中，您将传递所需的函数作为第三个参数:

In your code, you will pass the function you need as the third argument:

def f(x):
    return 2*x*(1-x)

iterate(seed, num, f)
#                  ^

或

def g(x):
    return 3*x*(2-x)

iterate(seed, num, g)
#                  ^

或者...

如果您不想每次都命名一个新函数，则可以选择传递一个匿名函数(即: lambda ):

If you don't want to name a new function each time, you will have the option to pass an anonymous function (i.e.: lambda) instead:

iterate(seed, num, lambda x: 3*x*(4-x))

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