Python：如何以灵活的参数顺序调用函数？

Question

Let us take an example. In certain libraries like "scipy.integrate" calling a function like "odeint" (integrating functions) has to be expressed as "odeint(func, y0, T, ...)" where "func" is a name of a function that has to be predefined with two parameters (y,t0), y vector and t0 a scalar.

The question is how to use "odeint" if the already defined function "func" is specified with two parameters but in the inverse order "(t0, y)".

Best regards.

Answer 1

You can use a lambda function to reorder the arguments like so:

odeint(lambda p, q: func(q, p), y0, T, ...)

Alternatively, you can supposedly swap the orders in the main call if all odeint does is call func on the arguments and does interact directly with the arguments:

odeint(func, T, y0, ...)

Answer 2

You can explicitly call parameters in arbitrary sequence:

def func(a, b, c):
    print('a = {}'.format(a))
    print('b = {}'.format(b))
    print('c = {}'.format(c))

x = 1
y = 2
z = 3

func(a = x, b = y, c = z)
func(c = z, b = y, a = x)
func(b = y, c = z, a = x)

PS I'm not on 100% sure, but try odeint(func, y0 = y0, T = T, ...)

or odeint(func, T = T, y0 = y0, ...) .