Python类与numpy数组相加

I have a question concerning overriding operands. I just tried to override the __add__(self, other) operator in a custom class, such that on of its elements (a numpy array) can be added to another numpy array. To make both directions of summing possible I both declared the __add__as well as the __radd__ operator. A small example:

我有一个关于重写操作数的问题。我只是试图覆盖自定义类中的__add __(self,other)运算符,这样就可以将其元素(一个numpy数组)添加到另一个numpy数组中。为了使两个求和方向成为可能,我都声明了__add__以及__radd__运算符。一个小例子:

import numpy as np

class MyClass():
    def __init__(self, x):
        self.x = x
        self._mat = self._calc_mat()


    def _calc_mat(self):
        return np.eye(2)*self.x

    def __add__(self, other):
        return self._mat + other

    def __radd__(self, other):
        return self._mat + other


def some_function(x):
    return x + np.ones(4).reshape((2,2))

def some_other_function(x):
    return np.ones(4).reshape((2,2)) + x


inst = MyClass(3)

some_function(x=inst)
some_other_function(x=inst)

Strangely, I get two different outputs. The first ouput, from some_function is just like expected:

奇怪的是,我得到两个不同的输出。来自some_function的第一个输出就像预期的那样:

Out[1]
array([[ 4.,  1.],
       [ 1.,  4.]])

The second output gives me something odd:

第二个输出给了我一些奇怪的东西:

Out[2]:    
array([[array([[ 4.,  1.],
       [ 1.,  4.]]),
        array([[ 4.,  1.],
       [ 1.,  4.]])],
       [array([[ 4.,  1.],
       [ 1.,  4.]]),
        array([[ 4.,  1.],
       [ 1.,  4.]])]], dtype=object)

Does somebody have an idea why is that?
Thanks, Markus :-)

有人知道为什么会这样吗?谢谢,马库斯:-)

1 个解决方案

#1

the issue is that numpy array is also implementing an __add__ method, and it is called before your __radd__

问题是numpy数组也在实现__add__方法,并在__radd__之前调用它。

you can see this answer for a solution: https://*.com/a/22633052/7033869

你可以看到这个答案的解决方案:https://*.com/a/22633052/7033869

#1