python函数参数传递的联系,如何在Python中将函数作为函数参数传递

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

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?

解决方案

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

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)

# ^

Or

def g(x):

return 3*x*(2-x)

iterate(seed, num, g)

# ^

Or ...

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))