Python-函数继承-更改关键字参数

Question

Is it possible to have a function defined with certain keyword arguments, and then to make a reference to the same function, but using different keyword argument values.

eg I have the following

def f_beta(x,a=2.7,b=3.05):
    """The un-normalised beta distribution function."""
    return math.pow(x, a - 1.0)*math.pow(1.0 - x, b - 1.0)

and I would like to do something equivalent to:

f = f_beta
g = f_beta(a=1.0, b=10.0)

where f is a copy of the initial function, and g is the same function but with different default values for the keyword arguments. Is there a way to do this for g without having to build f_beta this into a class, and without having to re-write various functions.

Motivation: I created a class which has a member function init_dist , which at some point I define in the __init__() via:

self.init_dist = f_beta

and would like to be able to pass in a new function.

I have looked at at the following:

• can-a-function-inherit-from-another-function-in-python
• python-inheritable-functions

and have had no luck in finding any answers, or where I should look for references.

Answer 1

Use functools.partial :

Python 2.7.6 (default, Jun 22 2015, 17:58:13) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from functools import partial
>>> import math
>>> def f_beta(x,a=2.7,b=3.05):
...     """The un-normalised beta distribution function."""
...     return math.pow(x, a - 1.0)*math.pow(1.0 - x, b - 1.0)
... 
>>> f = f_beta
>>> g = partial(f_beta, a=1.0, b=10.0)
>>> f()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f_beta() takes at least 1 argument (0 given)
>>> g()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f_beta() takes at least 1 argument (2 given)
>>> g(13)
-5159780352.0
>>> f(13, 1.0, 10.0)
-5159780352.0
>>>